Alloreactive cloned T cell lines. I. Interactions between cloned amplifier and cytolytic T cell lines

Several T cell clones have been derived by limiting dilution of secondary mixed leukocyte culture cells stimulated by H-2- and M locus (Mls)-disparate spleen cells. When examined for the expression of cytolytic activity and the ability to proliferate, these cell clones can be classified into two major categories. One type of cell is noncytolytic; when cultured with irradiated spleen cells, such clones proliferate in response to Mls determinants. Some, but not all, of these clones express Lyt-1 alloantigens. The other type of cell is cytolytic; these clones do not proliferate when cultured with irradiated allogeneic spleen cells unless supernatant fluid (SF) is added. These cytolytic clones express Lyt-2 alloantigens. Some cytolytic clones are specific for H-2Kd and others for H-2Dd alloantigens. Still other cytolytic cell clones exhibit cross-reactive lysis of different H-2-bearing tumor and Con A blast target cells. Noncytolytic T cell clones, when stimulated by Mls antigens, were examined for their ability to promote proliferation of cytolytic T cell clones. All of the noncytolytic cell clones tested were able to promote proliferation of cytolytic cell clones with the concomitant expression of cytolytic activity directed toward the original stimulating alloantigen (H-2d). Amplification of cytolytic activity was dependent upon stimulation of the noncytolytic amplifier T cell clones by Mls antigens. Specific alloantigen (signal 1), however, was not required for proliferation of the cytolytic cell clones; the amplifying signal (signal 2), delivered by the amplifier cell clones, was sufficient alone to promote proliferation of the cytolytic cell clones. Whereas proliferation of the amplifier cells was radiosensitive, the generation of the soluble amplifying signal was radioresistant. Amplification of cytolytic activity was observed when either amplifier cells were physically separated from responding cytolytic cells in Marbrook cultures or when cytolytic cells were cultured with SF collected from amplifier cell cultures. The amplifying factors were neither antigen specific nor strain specific and could be produced by Lyt-1- cells. The availability of cloned T cell lines that retain specific biologic function offers unique opportunities to characterize cell surface proteins and cell-cell interactions.     

Antigen-reactive T cell clones. I. Transcomplementing hybrid I-A-region gene products function effectively in antigen presentation

Studies in our laboratory and elsewhere have shown that it is possible to propagate antigen-specific murine T cells in vitro with resultant specific stepwise enrichment of antigen-induced proliferative cells. The proliferative responses of these T cells are antigen specific and dependent upon the presence of antigen-presenting cells (spleen cells) that share the I-A subregion with the proliferating T cell. Using techniques of soft-agar cloning, it has been further possible to isolate clones of antigen-reactive T lymphocytes from such long-term cultures. Data suggesting that these were clones of antigen-reactive T cells were obtained by studying the recognition of antigen in association with antigen-presenting cells with a panel of such clones of antigen-reactive T cells. Proof of clonality was obtained by subcloning. Clones derived from F1-immune mice can be divided into three separate categories: one clone recognizes antigen in association with antigen-presenting determinants of parent A and the F1; the second type recognizes antigen in association with antigen-presenting determinants of parent B and the F1; and the third type recognizes antigen only in association with antigen-presenting determinants of the F1 mouse. Genetic studies on the major histocompatibility complex requirements for antigen presentation to such F1-reactive T cell clones suggests that the hybrid antigen-presenting determinant in this system results from transcomplementation of products of the I-A region of haplotypes a and b. These studies support the concept developed in our laboratory that there exist unique F1 hybrid determinants on (A/J X C57BL/6) F1 cells and suggest that these determinants can be utilized physiologically by hybrid mice in immunocompetent cellular interactions.     

Clonal analysis of the Mls system. A reappraisal of polymorphism and allelism among Mlsa, Mlsc, and Mlsd

Only two sets of antigenic determinants are recognized by T lymphocytes at uniquely high precursor frequencies: those encoded by the MHC and those encoded by Mls. The structural as well as functional characteristics of MHC products have been extensively analyzed. In contrast, little information concerning the nature of Mls genes or their products is available. Although it was originally described (5, 6) that the Mls locus on chromosome 1 is composed of four alleles that encode polymorphic cell surface structures, the issues of polymorphism and allelism in the Mls system have been controversial for some time. In the present study, T cell clones were generated by continuous stimulation of B10.BR (H-2k, Mlsb) T cells by CBA/J (H-2k, Mlsd) stimulators and they were used to analyze the relationship of putative Mlsa, Mlsc, and Mlsd determinants. All clones proliferated in response to determinants expressed by CBA/J stimulators. In addition, each of these clones exhibited a second reactivity to either AKR/J (H-2k, Mlsa) or C3H/HeJ (H-2k, Mlsc) stimulators. No clone responded to both AKR/J and C3H/HeJ. These second specificities were defined to be for Mlsa or Mlsc determinants, respectively, by the response patterns of clones and unprimed T cells to stimulators derived from congenic strains, recombinant inbred (RI) strains, and backcross mice. Moreover, a segregation analysis of the (CBA/J X B10.BR)F1 X B10.BR backcross indicated that the Mlsa-like and Mlsc-like determinants expressed on CBA/J (Mlsd) cells are in fact encoded by nonallelic, unlinked genes. These findings suggest a new concept of the polymorphism and genetics of the Mls system. It is proposed that two distinct and nonallelic gene products express, respectively, the noncrossreacting Mlsa and Mlsc determinants, and that the Mlsd phenotype does not represent an independent genotype but rather reflects the concurrent expression of Mlsa and Mlsc. The Mls system, therefore, consists of at least two systems that are distinct both genetically and antigenically, and that may be of different biologic or physiologic significance as well.     

Tolerance of thymocytes to allogeneic I region determinants encountered prethymically. Evidence for expression of anti-Ia receptors by T cell precursors before their entry into the thymus

The present study has assessed whether precursor T cells express receptors specific for the recognition of allogeneic I region-encoded determinants before their entry into the thymus. Because the ability of thymocytes to proliferate in response to allogeneic stimulator cells was shown to primarily result from the recognition of allogeneic I region determinants, thymocytes must already express anti-Ia receptors. In contrast, the expression of anti- Ia receptors by functionally immature thymocyte precursors could not be directly assessed by mixed lymphocyte reaction reactivity. However, expression of anti-Ia receptors by thymocyte precursors could be assessed by their ability to be specifically tolerized by the allogeneic Ia determinants that they encountered during their differentiation. To determine whether T cell precursors could specifically recognize and be tolerized to allogeneic Ia determinants expressed prethymically, thymus- engrafted radiation bone marrow chimeras were constructed [A {arrow} A x B (Tx + A Thy)] such that strain A T cells would be differentiating within a syngeneic strain A thymus but would have been previously exposed to the allogeneic strain B Ia determinants of the irradiated A x B host. The strain A thymocytes from these experimental animals were indeed tolerant to the extrathymic allogeneic strain B Ia determinants expressed by the irradiated host. Such tolerance was not mediated by detectable suppression and was not explained by the presence intrathymically of extrathymic allogeneic Ia determinants. Thus, these results suggest that T cell precursors can be specifically tolerized entry into the thymus. In addition, the failure to detect the generation of thymocytes with specificity for the allogeneic Ia determinants of the irradiated host, which were not deleted prethymically, argues that novel anti-allo Ia receptor specificities are not generated intrathymically.     

Multiple functional sites on a single Ia molecule defined using T cell clones and antibodies with chain-determined specificity

Monoclonal antibodies (mAb) were used to inhibit the proliferation of antigen-reactive (C57BL6/J X A/J)F1 restricted T cell clones. We have been able to subdivide these F1 restricted T cell clones into two groups: one of which recognizes the A alpha k A beta b molecule and the other group which recognizes the A alpha b A beta k molecule. Using clones with defined reactivities, we could assign the reactivities of monoclonals to the A alpha or A beta chains. By immunoprecipitation and two-dimensional analysis of Ia molecules from F1 spleen cells, we could independently map the reactivities of the mAb as being determined by the A alpha or A beta chain. To date, these two methods of chain localization of the antibody reactivity have agreed. Further, the differential blocking of the A alpha k A beta b restricted T cell clones suggests that there exists more than one restriction site per Ia molecule. Increasing the number of possible functional Ia restriction sites, either through combinatorial association of alpha and beta chains or by using more than one site per molecule, should increase the number of ways Ia molecules can function in antigen presentation.     

Induction of neonatal tolerance to H-2k in B6 mice does not allow the emergence of T cells specific for H-2k plus vaccinia virus

Thymocytes and spleen cells from C57BL/6 mice (H-2b) neonatally tolerized to H-2k alloantigens do not generate an anti-vaccinia response restricted to H-2Kk when adoptively transferred to appropriate irradiated hosts. This is in sharp contrast to the case for negatively selected C57BL/6 spleen cells acutely depleted of alloreactivity. No evidence for suppression was found in cell mixture experiments. We have shown elsewhere that our neonatally tolerized animals have a centrally induced delection-type tolerance in the absence of obvious suppression.2 We now suggest that in the neonatally tolerized mouse, chronic, central delection of anti-H-2k clones during early T cell ontogeny eliminates the major source of cells able to give rise, via somatic mutation and expansion, to anti-H-2Kk + vaccinia specific cytotoxic T lymphocyte precursors (CTL-P) in the adult. A similar mechanism may operate in the (k + b) leads to b chimera; however, the presence of H-2kxb accessory and presenting cells may permit the eventual generation (via cross-stimulation) of an H-2k-restricted vaccinia-specific repertoire. This would account for our observation of such "aberrant recognition" CTL-P emerging in the spleens of older (k x b) leads to b chimeras.     

The I-Ab mutant B6.C-H-2bm12 allows definition of multiple T cell epitopes on I-A molecules

The experiments presented in this study demonstrate that there exist at least two functional epitopes on an I-A molecule that can be recognized by T cell clones. By comparing the abilities of spleen cells from C57BL/6 mice and the congenic I-A mutant line B6.C-H-2bm12 to stimulate alloreactive T cell clones specific for the I-Ab molecule, we have discriminated two sets of clones, those recognizing the I-Ab and I-Abm12 molecule equally well and those able to recognize only the I-Ab molecule. These results imply that the two sets of clones have different receptors for I-A and that they therefore recognize separate epitopes on the I-A molecule. We have similarly been able to separate T cell clones, both alloreactive and L-glutamic acid60-L-alanine30-L-tyrosine10-reactive, specific for the Ab alpha Ak beta hybrid molecule into two groups based on their ability to recognize bm 12 spleen cells. Although the recognition of bm 12 spleen cells by these clones was unexpected since none of them responds to B6 spleen cells, these data again allow us to conclude that these groups of clones have different receptors for the same I-A molecule and therefore that they recognize distinct epitopes on the molecule. Additional studies, in which monoclonal anti-I-A antibodies were used to block the stimulation of T cells by stimulator or antigen-presenting cells, have demonstrated that this blockade can be a steric effect and therefore is not necessarily indicative of direct competition between the antibody and the T cell for the same site on an I-A molecule. Although this study does not reveal the physical nature of an I region-controlled "antigen-restriction site," we can suggest that increasing the number of possible functional Ia restriction sites either through combinatorial association of alpha and beta chains or by using more than one site per molecule will increase the number of configurations the ternary complex of Ia, antigen and T cell receptor(s) can form.     

A clone-specific monoclonal antibody that inhibits cytolysis of a cytolytic T cell clone

Monoclonal antibody 384.5 specifically inhibited cytolysis of P-815 target cells by cloned L3 cytotoxic T lymphocyte (CTL) effector cells. The lytic activity of other cloned CTL that have other distinct specificities was not affected. Antibody 384.5 did not inhibit the cytolytic activity of bulk populations of C57BL/6 mixed lymphocyte culture (MLC) cells. Concanavalin A-facilitated cytolysis by T cell clone L3 but not T cell clone B18 was inhibited by antibody 384.5, whereas phytohemagglutinin-facilitated cytolysis by L3 cells was not strongly inhibited. Antibody 384.5 binds specifically to L3 cells but not to several other T lymphocytes clones, or to a detectable portion of populations of primary MLC cells, normal spleen, thymus, lymph node, or bone marrow cells. In contrast, C57BL/6 anti-B10.A(5R) secondary MLC cells (genetically enriched for reactivity against the H-2Dd region gene products) contained a small population which reacted with the antibody 384.5. The determinant detected by antibody 384.5 was susceptible to trypsin treatment, and was reexpressed after overnight incubation. These results suggest that the monoclonal antibody 384.5 detects an endogenously synthesized clone-specific determinant associated with the cytolytic activity of the L3 CTL clone. These properties make antibody 384.5 an attractive candidate for an antibody that reacts with the antigen-recognition site of a cytolytic T cell antigen receptor.     

The role of H-2-linked genes in helper T cell function. VII. Expression of I region and immune response genes by B cells in bystander help assays

The mode of action by bystander helper T cells was investigated by priming (responder X nonresponder) (B6A)F1 T cells with poly-L-(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys [(TG)-A--L] and titrating the ability of these cells to stimulate an anti-sheep red blood cell (SRBC) response of parental B cells and macrophages in the presence of (TG)-A--L. Under limiting T cell conditions, and in the presence of (TG)-A--L, (TG)-A--L-responsive T cells were able to drive anti-SRBC responses of high-responder C57BL/10.SgSn (B10) B cells and macrophages (M0), but not of low-responder (B10.A) B cells and M0. Surprisingly, the (TG)-A--L-driven anti-SRBC response of B10.A B cells was not restored by addition of high-responder acessory cells, in the form of (B6A)F1 peritoneal or irradiated T cell-depleted spleen cells, or in the form of B10 nonirradiated T cell-depleted spleen cells. These results suggested that (TG)-A--L-specific Ir genes expressed by B cells controlled the ability of these cells to be induced to respond to SRBC by (TG)-A--L-responding T cells, implying that direct contact between the SRBC-binding B cell precursor and the (TG)-A--L-responsive helper T cells was required. Analogous results were obtained for keyhold limpet hemocyanin (KLH)-driven bystander help using KLH-primed F1 T cells restricted to interact with cells on only one of the parental haplotypes by maturing them in parental bone marrow chimeras. It was hypothesized that bystander help was mediated by nonspecific uptake of antigen [(TG)-A--L or KLH] by SRBC-specific b cells and subsequent display of the antigen on the B cell surface in association with Ir of I-region gene products, in a fashion similar to the M0, where it was then recognized by helper T cells. Such an explanation was supported by the observation that high concentrations of antigen were required to elicit bystander help. This hypothesis raises the possibility of B cell processing of antigen bound to its immunoglobulin receptor and subsequent presentation of antigen to helper T cells.     

T cell and non-T cell compartments can independently determine resistance to Leishmania major

In experimental murine cutaneous leishmaniasis caused by Leishmania major (Lm), the cellular determinants governing development of protective or exacerbative T cells are not well understood. We, therefore, attempted to determine the influence of T cell and non-T cell compartments on disease outcome. To this end, T cell chimeric mice were constructed using adult thymectomized lethally irradiated, bone marrow-reconstituted (ATXBM) animals of genetically resistant, C57BL/6, or susceptible, BALB/c, backgrounds. These hosts were engrafted with naive T cell populations from H-2-congenic susceptible, BALB.B6-H-2b, or resistant, C57BL/6.C-H-2d, animals, respectively. Chimeric mice were then infected with Lm, and disease outcome was monitored. BALB/c T cell chimeric mice, BALB/c ATXBM hosts given naive C57BL/6.C-H-2d T cells, resolved their infections as indicated by reductions in both lesion size and parasite numbers. Furthermore, the mice developed typical Th1 (interferon[IFN]-gamma hiinterleukin[IL]-4lo) cytokine patterns. In contrast, both sham chimeric, BALB/c ATXBM hosts given naive BALB/c T cells, and control irradiated euthymic mice succumbed to infection, producing Th2 profiles (IFN-gamma loIL-4hiIL-10hi). C57BL/6 T cell chimeras, C57BL/6 ATXBM hosts given naive BALB.B6-H-2b T cells, resolved their infections as did C57BL/6 sham chimeras and euthymic controls. Interestingly, whereas C57BL/6 control animals produced Th1 cytokines, chimeric animals progressed from Th0 (IFN-gamma hiIL-4hiIL- 10hi) to Th2 (IFN-gamma loIL-4hiIL-10hi) cytokine profiles as cure ensued. Both reconstitution and chimeric status of all mice were confirmed by flow cytometry. In addition, T cell receptor V beta usage of Lm-specific blasts was determined. In all cases, V beta use was multiclonal, involving primarily V beta 2, 4, 6, 8.1, 8.2, 8.3, 10, and 14, with relative V beta frequencies differing between H-2b and H-2d animals. Most importantly, however, these differences did not segregate between cure and noncure outcomes. These findings indicate that: (a) genetic traits determining cure in Lm infection can direct disease outcome from both T cell and non-T cell compartments; (b) the presence of the curing genotype in only one compartment is sufficient to confer cure; (c) curing genotype T cells autonomously assume a Th1 cytokine profile-mediating cure; (d) noncuring genotype T cells can mediate cure in a curing environment, despite the onset of Th2 cytokine production; and lastly, (e) antigen specificity of responding T cells, as assessed by V beta T cell receptor diversity, is not a critical determinant of disease outcome.     

Requirement of dendritic cells and B cells in the clonal deletion of Mls-reactive T cells in the thymus

The present study was performed to identify cells responsible for the elimination of T cells reactive with minor lymphocyte-stimulating (Mls) antigens during T cell development. Experiments were carried out in a fetal thymus organ culture (FTOC) system. To examine the tolerance-inducing activity, various populations of cells from adult CBA/J (Mls-1a) mice were injected into deoxyguanosine (dGuo)-treated FTOC of C3H/He (Mls-1b) mice with a microinjector, and 2 d later, the thymus lobes were injected with fetal thymus cells from C3H/He mice as T cell precursors. After 14 d of cultivation, cells were harvested and assayed for the expression of the T cell receptor V beta 6 element. The absence or marked reduction of T cells expressing V beta 6 at high levels (V beta 6high) was regarded as indicating the deletion of Mls-1a-reactive T cells. T cell-depleted populations of thymic as well as splenic cells from CBA/J mice were able to induce clonal deletion. Further characterization of the effector cells was carried out by fractionating the spleen cells before injecting them into dGuo-FTOC. None of the dish-adherent population, dish-nonadherent population, or purified B cells alone were able to induce clonal deletion, whereas the addition of purified B cells to adherent cells restored tolerance inducibility. It was further shown that a combination of CBA/J B cells and C3H/He dendritic cells was effective in eliminating Mls-reactive clones. These results indicate that for the deletion of clones reactive with Mls antigens during T cell development in the thymus, both DC and B cells are required.     

Evidence for mouse Th1- and Th2-like helper T cells in vivo. Selective reduction of Th1-like cells after total lymphoid irradiation

Purified CD4+ BALB/c spleen T cells obtained 4-6 wk after total lymphoid irradiation (TLI) helped normal syngeneic B cells to produce a vigorous antibody response to TNP keyhole limpet hemocyanin in adoptive cell transfer experiments. However, the same cells failed to transfer delayed-type hypersensitivity to the adoptive hosts as measured by a foot pad swelling assay. In addition, purified CD4+ cells from TLI-treated mice were unable to induce graft vs. host disease in lethally irradiated allogeneic C57BL/Ka recipient mice. In response to mitogen stimulation, unfractionated spleen cells obtained from TLI mice secreted normal levels of IL-4 and IL-5, but markedly reduced levels of IL-2 and INF-gamma. A total of 229 CD4+ clones from spleen cells of both normal and TLI-treated mice were established, and the cytokine secretion pattern from each clone was analyzed. The results demonstrate that the ratio of Th1- and Th2-like clones in the spleens of normal BALB/c mice is 1:0.6, whereas the ratio in TLI mice is approximately 1:7. These results suggest that Th2-like cells recover rapidly (at approximately 4-6 wk) after TLI treatment and account for the early return of antibody helper activity and secretion of IL-4 and IL-5, but Th1-like cells recover more slowly (in approximately 3 mo) after irradiation, and this accounts for the deficit in cell-mediated immunity and the reduced amount of IL-2 and IFN-gamma secretion.     

Antigen-specific T cell clones restricted to unique F1 major histocompatibility complex determinants. Inhibition of proliferation with monoclonal anti-Ia antibody

The existence of T cells specific for soluble antigens in association with unique F(1) or recombinant major histocompatibility complex (MHC) gene products was first postulated from studies on the proliferative response of whole T cell populations to the antigen poly(Glu(55)Lys(36)Phe(9))(n) (GL). In this paper we use the newly developed technology of T lymphocyte cloning to establish unequivocally the existence of such cells specific for GL and to generalize their existence by showing that F(1)- specific cells can be isolated from T cell populations primed to poly(Glu(60)Ala(30)Tyr(10))(n) (GAT) where such clones represent only a minor subpopulation of cells. Gl.4b-primed B10.A(5R) and GAT-primed (B10.A × B10)F(1) lymph node T cells were cloned in soft agar, and the colonies that developed were picked and expanded in liquid culture. The GL-specific T cells were then recloned under conditions of high-plating efficiency to ensure that the final colonies originated from single cells. T cells from such rigorously cloned populations responded to stimulation with GIL but only in the presence of nonimmune, irradiated spleen cells bearing (B10.A × B10)F(1) or the syngeneic B 10.A(5R) recombinant MHC haplotype. Spleen cells from either the B10 or B 10.A parental strains failed to support a proliferative response, even when added together. (B10 × B10.D2)F(1) and (B10 × B10.RIII)F(1) spleen cells also supported a proliferative response but (B10 × B10.Q)F(1) and (B10 X B10.S)F(1) spleen cells did not. These results suggested that the T cell clones were specific for GL[phi} in association with the β(AE)(b)-α(E) (k,d,r,) Ia molecule and that recognition required both gene products to be expressed in the same antigen-presenting cells. Support for this interpretation was obtained from inhibition experiments using the monoclonal antibody Y-17 specific for a determinant on the β(AE)(b)-αE Ia molecule. Y-17 completely inhibited the proliferative response of a GL-specific clone but had no effect on the response of either a PPD-specific or GAT-specific clone, both of which required the β(A)-α(A) Ia molecule as their restriction element. No evidence could be found for the involvement of suppressor T cells in this inhibition. We therefore conclude that the phenomenon of F(1)-restricted recognition by proliferating T cells results from the presence of antigen- specific clones that must recognize unique F(1) or recombinant Ia molecules on the surface of antigen-presenting cells in addition to antigen in order to be stimulated.     

Mechanisms of genetic resistance to Friend virus leukemia. III. Susceptibility of mitogen-responsive lymphocytes mediated by T cells

Friend leukemia virus (FV) suppressed the proliferative responses of spleen, lymph node, marrow, and thymus cell populations to various T- and B-cell mitogens. Cells taken from mice, e.g. BALB/c genetically susceptible to leukemogenesis in vivo were much more susceptible to suppression of mitogenesis in vitro than similar cells from genetically resistant mice, e.g., C57BL/6. Nylon wool-purified splenic T cells from BALB/c and C3H mice lost susceptibility to FV-induced suppression of mitogenesis but became suppressible by addition of 10% unfiltered spleen cell. Thus, FV mediates in vitro suppression of lymphocyte proliferation indirectly by "activating" a suppressor cell. The suppressor cell adhered to nylon wool but not to glass wool or rayon wool columns. Pretreatment of spleen cells with carbonyl iron and a magnet did not abrogate the suppressor cell function. Suppressor cells were not eliminated by treatment with rabbit antimouse immunoglobulin (7S) and complement (C). However, high concentrations of anti-Thy-1 plus C destroyed suppressor cells of the spleen; thymic suppressor cells were much more susceptible to anti-Thy-1 serum. Nude athymic mice were devoid of suppressor cells and their B-cell proliferation was relatively resistant to FV-induced suppression in vitro. The suppressor cells in the thymus (but not in the spleen) were eliminated by treatment of mice with cortisol. Thus, FV appears to mediate its suppressive effect on mitogen-responsive lymphocytes by affecting "T-suppressor cells." Spleen cells from C57BL/6 mice treated with 89Sr to destroy marrow-dependent (M) cells were much more suppressible by FV in virto than normal C57BL/6 spleen cells. However, nylon-filtered spleen cells of 89Sr-treated C57BL/6 mice were resistant to FV-induced suppression in vitro, indicating that the susceptibility of spleen cells from 89Sr-treated B6 mice is also mediated by suppressor cells. Normal B6 splenic T cells were rendered susceptible to FV-induced suppression of mitogenesis by addition of 10% spleen cells from 89Sr-treated B6 mice. Thus, M cells appear to regulate the numbers and/or functions of T-suppressor cells which in turn mediate the immunosuppressive effects of FV in vitro. Neither mitogen-responsive lymphocytes nor T-suppressor cells are genetically resistant or susceptible to FV. The genetic resistance to FV is apparently a function of M cells, both in vitro as well as in vivo.     

Monoclonal antibodies that recognize the product controlled by a gene in the I-J subregion of the mouse H-2 complex

The B cell hybridomas producing monoclonal antibodies (E10, D7, F4, H6, and D4) were established by the fusion of P3U1 or NS-1 murine myeloma cell lines and spleen cells of B10.A(5R) mice hyperimmunized with mitomycin C-treated B10.A(3R) spleen and thymus cells. Two types of monoclonal antibodies specific for the products controlled by a gene in the I-Jb subregion of the H-2 complex were characterized: one specific for the private type of I-Jb determinant, the other recognizing the cross-reactive determinant between the I-Jb and I-Jd products. By using these monoclonal reagents, the I-J-encoded product on the antigen-specific suppressor T cells was found to be expressed on their soluble suppressor factors. Furthermore, the I-Jb products were successfully detected not only on the T cell hybridoma with suppressor activity specific for keyhole limpet hemocyanin (KLH), but also on KLH-primed suppressor T cells enriched by antigen-coated petri dishes and concanavalin A-induced thymocyte blasts of C57BL/6 mice by complement-dependent cytotoxic assays and membrane fluorescence techniques.     

Dendritic cells are accessory cells for the development of anti- trinitrophenyl cytotoxic T lymphocytes

This study establishes that dendritic cells (DC) are the critical accessory cells for the development of anti-trinitrophenol (TNP) cytotoxic T lymphocytes (CTL) in vitro. We developed a model in which nylon wool-nonadherent spleen cells were used both as the responding and stimulating cells, the latter having been TNP-modified and x- irradiated. Thy-1-bearing CTL developed in C57BL/6, B6D2F1, and CBA mice only when small numbers of DC were added. Maximal responses in 5-d cultures were achieved with 0.5-1 DC/100 responding T cells. The DC did not have to be TNP modified directly. Anti-Ia and complement inactivated accessory cells, whereas similar treatment of the responders had no effect. DC exposed to ultraviolet radiation were ineffective, but x-irradiated DC were fully active. Culture media from DC, or from DC-nylon wool-passed spleen T cell cocultures that contained abundant CTL, would not substitute for viable DC. Enriched preparations of macrophages (M phi) were obtained from blood, peritoneal cavity, and spleens of BCG-immune and unprimed mice. M phi added at doses of 0.2-4% were weak or inactive as accessory cells. The level of Ia antigens on test M phi populations was quantitated and visualized by binding of a radioiodinated monoclonal anti-I-Ab,d antibody, clone B-21. M phi that bore substantial amounts of Ia from all organs were weak accessory cells. Addition of M phi to DC-T cell cocultures produced inhibitory effects, usually at a dose of 2% M phi. In contrast, 0.5% Ia-bearing M phi from BCG-immune boosted mice inhibited > 80% of the DC-mediated CTL response. Addition of indomethacin reversed M phi inhibition, and 10(-9) M prostaglandin E2 in turn blocked the indomethacin effect. Indomethacin also restored a low level of accessory cell function in immune-boosted adherent peritoneal cells, but not in preparations of monocytes and spleen M phi. Small numbers of DC were identified in preparations of immune- boosted peritoneal cells and may have accounted for the observed accessory activity. We conclude that the development of anti-TNP CTL is an immune response in which (a) DC are the critical accessory cells; (b) Ia-bearing M phi are weak or inactive; and (c) M phi can inhibit DC- mediated response by an indomethacin-sensitive mechanism.     

GENETIC CONTROL OF IMMUNE RESPONSES IN VITRO : IV. CONDITIONS FOR COOPERATIVE INTERACTIONS BETWEEN NONRESPONDER PARENTAL B CELLS AND PRIMED (RESPONDER x NONRESPONDER) F1 T CELLS IN THE DEVELOPMENT OF AN ANTIBODY RESPONSE UNDERIr GENE CONTROL IN VITRO

The conditions for cooperative interactions between nonresponder B10.S B cells and GAT-primed irradiated (C57BL/6 x SJL)F₁ T cells in the response by cultures of mouse spleen cells to GAT were investigated. GAT-specific antibody responses could be elicited by soluble GAT in cultures of GAT-primed irradiated (C57BL/6 x SJL)F₁ T cells with C57BL/6 B cells but not with B10.S B cells. In contrast, when GAT was presented to the cultures on F₁ macrophages or as aggregates of GAT with MBSA, GAT-specific PFC responses were observed with both B10.S or C57BL/6 B cells. Irradiated GAT-primed T cells were nevertheless essential for the development of these responses. The GAT-specific response of B10.S B cells in these cultures was inhibited by the addition of soluble GAT at culture initiation. These results indicate that genetic disparity at Ir loci is not an absolute barrier to T-B-cell cooperative interactions in the response to antigens under Ir gene control. The significance of these data for the function of Ir gene products in immunocompetent cells is discussed.     

Allogeneic cell therapy in murine B-cell leukemia (BCL1): 2. The role of non-activated and rIL-2-activated CD4+ and CD8+ T cells in immunotherapy for leukemia

Graft-versus-leukemia (GVL) effects play a key role in the elimination of residual leukemia cells in the course of allogeneic bone marrow transplantation (alloBMT). GVL effects can also be induced by donor lymphocyte infusion following alloBMT. We have investigated the role of CD4+ and CD8+ T cells in the development of GVL in mice with B-cell leukemia/lymphoma (BCL1) following allogeneic cell therapy. Sublethally irradiated (C57BL/6 x BALB/c)F1 mice were intravenously inoculated with 10(5) BCL1 cells and given untreated or recombinant human Interleukin-2 (rIL-2)-activated C57BL/6 spleen cells. Effective elimination of clonogenic BCL1 cells was confirmed by adoptive transfer of spleen cells obtained from treated mice into secondary BALB/c recipients. GVL effects were maintained after inactivation of CD4+ cells with monoclonal anti-CD4 antibodies in the inoculum, while inactivation of CD8+ cells with monoclonal anti-CD8 antibodies resulted in complete loss of GVL effects induced both by resting and rIL-2-activated allogeneic spleen lymphocytes. These results indicate that Thy-1 cells play the major role in the induction of GVL effects, mediated by C57BL/6 effector T cells in this model. Since the number of natural killer (NK) cells also increased during in vitro culture with rIL-2, their contribution, especially that of CD8+ NK cells, in GVL effects mediated by rIL-2-activated CD8+ cells cannot be ruled out.     

Two distinct types of helper T cells involved in the secondary antibody response: independent and synergistic effects of Ia- and Ia+ helper T cells.

We have described here two distinct types of carrier-specific helper T cells which act independently and synergistically to augment the B-cell response to a hapten. They are separable by passage through a nylon wool column. The first type of helper T cell, which we designate as Th1, is nylon nonadherent, and can help the response of hapten-primed B cells only if the haptenic and carrier determinants are present on a single molecule (cognate interaction). The second type of helper T cell, Th2, adheres to the nylon wool column, and can help the B-cell response to a hapten coupled to a heterologous carrier upon stimulation with unconjugated relevant carrier (polyclonal interaction). The addition of a small number of Th2 to the mixture of Th1 and B cells significantly augmented the net response to the hapten carrier conjugate. Both Th1 and Th2 cells belong to the Lyt-1+,2-,3- subclass. Th1 has no detectable Ia antigen, whereas Th2 is killed by certain anti-Ia antisera and complement. The Ia antigen detected on Th2 was found to be controlled by a locus in the I-J subregion. The results clearly established the fact that there are two distinct pathways in the T- and B-cell collaboration, which involves two different subsets of carrier-specific helper T cells.     

应用扩增的Treg预防异基因骨髓移植后移植物抗宿主病的实验研究

目的：探讨扩增后的CD4+CD25+调节T细胞(regulatory T cell ,Treg)输注对异基因骨髓移植(allo-BMT)后小鼠移植物抗宿主病(GVHD)的影响。方法：利用免疫磁珠法分选小鼠Treg细胞； 以抗鼠 CD3ε 单抗、抗鼠CD28 单抗 、鼠重组 IL-2及辐射过的Balb/C小鼠脾细胞为共刺激因子，扩增TREG细胞；建立C57BL/6→BALB/c小鼠allo-BMT模型,接受移植小鼠随机分为3组,移植骨髓后6-8小时后分别予尾静脉输注扩增的Treg细胞、CD4+CD25-T细胞和RPMI 1640培养液(空白对照)。以移植后GVHD表现,肝、脾、小肠组织病理形态、生存期为观察指标并进行组间比较。结果：经免疫磁珠法分选可获得高纯度(91.80±2.15)%及具较强活力(97.58±1.23)%的Treg细胞；移植后(四周左右)的扩增后Treg细胞移植组小鼠肝、脾、小肠GVHD病理损害较同期CD4+CD25-T细胞移植组与空白对照组小鼠有一定程度的减轻。3组小鼠移植后平均存活时间分别为（61. 45±27. 88）天、(18.58±12. 39)天和(26. 37±15. 65)天, 扩增后Treg细胞移植组小鼠平均存活时间较CD4+CD25-T细胞、空白对照组小鼠延长(P<0.05)。结论：allo-BMT后输注增殖的Treg细胞可以减轻移植后GVHD程度,延长小鼠生存时间。