T-cell immune responses in Mycobacterium avium-infected mice.

Mycobacterium avium infection was substantially more severe in C57BL/6 (Bcgs) than in (C57BL/6 x DBA/2)F1 hybrid (Bcgr) mice both in terms of bacterial growth in the spleens and lungs and in host survival. Prior Mycobacterium bovis BCG vaccination resulted in increased resistance as well as enhanced tuberculin hypersensitivity to both PPD-S (Mycobacterium tuberculosis) and PPD-A (M. avium). Mice heavily infected with M. avium were used as T-cell donors in an adoptive transfer system. Substantial resistance was observed for both recipient hosts regardless of the genotype of the donor strain. Transfer of resistance was ablated by treatment of the immune spleen cells with anti-Thy 1.2 monoclonal antibody and complement or by cyclophosphamide treatment. Spleen cells which were monodepleted of L3T4+ or Lyt-2+ T cells did not lose their ability to transfer resistance against a subsequent challenge. However, when these cells were doubly deleted, all resistance was ablated in both the BCG-susceptible and -resistant mice. The recipient host expressed a detectable adoptive immune response although the donor had been unable to reduce the growth of the primary M. avium infection in vivo.     

Memory T cell-mediated resistance to Mycobacterium tuberculosis infection in innately susceptible and resistant mice.

The memory T cell immune response to Mycobacterium tuberculosis infection was examined in strains of mice which vary in their natural susceptibility to Mycobacterium bovis BCG infection. Naturally susceptible (NS) C57BL/6 and naturally resistant (NR) B6D2 F1 hybrid mice were infected with a sublethal dose of M. tuberculosis and then given antibiotic therapy beginning 2 weeks postinfection. T cells from both strains of mice transferred significant levels of resistance to syngeneic mice challenged aerogenically with M. tuberculosis. This memory response was not substantially reduced by depletion of either L3T4+ or Lyt2+ T cells from the donor mice but was ablated by depletion of both T cell subsets. Cyclophosphamide pretreatment of C57BL/6 memory T cell donors also ablated the resistance transferred to recipient mice. In contrast, B6D2 memory T cells were not affected by cyclophosphamide treatment, suggesting that differences may exist in the metabolic state of the memory T cells in the two donor strains, despite the fact that they both develop similar levels of acquired resistance to a subsequent tuberculous challenge.     

Adoptive transfer of protection against Trypanosoma cruzi with lymphocytes and macrophages.

Female C57BL/6J mice were infected with Trypanosoma cruzi and subsequently given macrophages or lymphocytes from syngeneic donors which had recovered from the acute infection. Mice which received immune peritoneal macrophages, splenic lymphocytes, or lymph node lymphocytes developed lower mean parasitemias and cumulative mortalities than did recipients of nonimmune cells. Neither peritoneal lymphocytes nor splenic macrophages were protective, however. These studies indicate that splenic and lymph node lymphocytes are effective in transferring protection against T. cruzi, whereas the macrophage is somewhat less effective.     

Infection of mice with Mycobacterium avium primes CD8+ lymphocytes for apoptosis upon exposure to macrophages

Mycobacterial infection is associated with granuloma formation in which the presence of apoptosis has been recognized. The role of CD4+ T and CD8+ T cells in host protection against mycobacterial infections has been demonstrated. Previous studies, however, have shown that CD8+ T cells have a limited role in host defense against Mycobacterium avium infection, and we hypothesize that M. avium infection could lead to T cell apoptosis. To investigate this hypothesis, C57BL/6 mice were infected with M. avium strain 101, and the rate of apoptosis of splenic lymphocytes cultured ex vivo with peritoneal macrophages was determined and compared with that of controls. When exposed to infected macrophages ex vivo, splenic lymphocytes from M. avium-infected mice underwent apoptosis, as determined by the TUNEL assay. This increased T cell apoptosis above the control level was observed after 3 weeks but not after only 1 week of infection in mice. No splenic T cell apoptosis was observed when lymphocytes from Mycobacterium smegmatis-infected mice were cultured in the presence of M. smegmatis-infected peritoneal macrophages. Likewise, macrophages infected in vitro with heat-killed M. avium did not trigger T cell apoptosis. Culture of macrophages in different chamber from lymphocytes, separated by a transwell membrane, was not associated with increase of apoptosis compared with uninfected control, suggesting a requirement for direct cell-cell interactions to trigger lymphocyte apoptosis. Using a double staining TUNEL followed by anti-mouse CD4 or anti-mouse CD8 monoclonal antibodies, it was observed that only CD8+ T cells but not CD4+ T cells underwent apoptosis at 3 weeks of infection. In conclusion, M. avium infection in C57/BL6 mice for 3 weeks renders CD8+ T cells prone to apoptosis when exposed ex vivo to macrophages infected with M. avium.     

不同种鼠对实验脑型疟发生的影响研究

目的比较昆明小鼠和C57BL/6小鼠作为种鼠对实验脑型疟模型的影响。方法分别以伯氏疟原虫ANKA株感染C57BL/6小鼠和昆明小鼠作为传代用种鼠,当种鼠原虫率为5%～15%时接种子代C57BL/6小鼠,观察两组小鼠原虫率、脑型疟发生率以及死亡率。同时,通过脑组织切片和脑部淋巴细胞的流式检测,观察两组发生脑型疟小鼠的脑部微血管中感染疟原虫红细胞和CD8＋T细胞的粘附情况,另外,通过感染CD8＋TKO小鼠,证实CD8＋T细胞在两组小鼠发生脑型疟中的作用。结果用昆明小鼠作为种鼠的实验组的原虫率和脑型疟发生率均明显高于用C57BL/6小鼠作为种鼠的实验组,发生脑型疟小鼠的脑部组织切片发现,脑部微血管可见明显的感染疟原虫红细胞的粘附和CD8＋T淋巴细胞浸润;而用昆明小鼠作为种鼠感染CD8＋T细胞缺失的C57BL/6小鼠并不能诱导实验脑型疟的发生。结论与C57BL/6小鼠相比,昆明小鼠作为种鼠的实验组的脑型疟发病率更高,而且感染疟原虫红细胞和CD8＋T细胞在脑部微血管内的粘附也是该脑型疟发生的主要因素,因此,更适合用于实验脑型疟模型的建立及其机制的探讨。     

Splenic dendritic cells from the non-obese diabetic mouse induce a prolonged proliferation of syngeneic T cells. A role for an impaired apoptosis of NOD T cells?

In this study we have tried to detect abnormalities in the immunophenotype and/or function of dendritic cells from the non-obese diabetic mouse (NOD DC), that might be related to islet autoimmunity. The immunophenotype of NOD splenic DC did not show significant abnormalities as compared with the immunophenotype of splenic DC from C57BL/10 mice. Furthermore, NOD splenic and lymph node DC stimulated proliferation of syngeneic T cells as efficiently as DC from C57BL/10 and BALB/c mice. The allogeneic response induced by NOD DC was similar to or only slightly lower than the response induced by C57BL/10 DC. Both a normal immunophenotype of NOD DC and efficient T cell stimulation were observed regardless of the stage of diabetes development. However, the syngeneic T cell proliferation induced by NOD splenic DC, but not by C57BL/10 splenic DC, was significantly prolonged, and it was accompanied by an increased proportion of activated/memory CD4(+)cells. We demonstrated that during the interaction of NOD cells fewer apoptotic cells were generated as compared with the interaction of C57BL/10 cells. Thus, the prolonged T cell response during the syngeneic interaction between NOD DC and T cells might be due to an impaired apoptosis induction. The impaired apoptosis might be of critical importance in the development of islet autoimmunity in the NOD mouse.     

Difference between the lymph node response to injection of autosensitized T lymphocytes and that in a graft-versus-host reaction

Thymus (T) lymphocytes autosensitized in vitro were shown in previous studies to produce enlargement of draining popliteal lymph nodes upon injection into the footpads of syngeneic rats. Specific autoreactive effector lymphocytes were found to be recruited within these lymph nodes. In the present study, the cellular basis of lymph node enlargement in mice by autosensitized lymphocytes was compared with that produced in a graft-vs.-host (GvH) reaction. T lymphocytes of C3H mice were autosensitized against syngeneic fibroblasts in vitro for 16 to 18 h in the absence of serum, and 10⁷ lymphocytes were injected into the footpads of syngeneic mice. Control lymphocytes were incubated without fibroblasts. The GvH reaction was produced by injecting 10⁷ C3H T lymphocytes into the footpads of (C3H × C57BL)F₁ adult recipients. The index of relative enlargement of the draining popliteal lymph nodes was measured 6 days after injection. Experiments were done to identify the origin of the lymph node cells in these reactions. Irradiation of the donor lymphocytes (1000 r) or the recipient mice (550 r) was used to prevent proliferation of the lymphocytes of either origin. The participation of recipient T lymphocytes in lymph node enlargement was investigated by using thymectomized mice. The following results were obtained. 1) The GvH lymph node enlargement was found to depend on proliferation of the donor T lymphocytes, but did not seem to require the participation of radiosensitive cells within the recipient mice. 2) In contrast, the response of the lymph nodes to autosensitized donor T lymphocytes depended on the function of radiosensitive T lymphocytes within the syngeneic recipients. The autosensitized donor lymphocytes themselves did not have to proliferate to recruit the response of recipient T lymphocytes. 3) It was found that recruitment of recipient lymph node cells could be super-imposed upon a conventional GvH reaction by presensitizing the C3H donor lymphocytes in vitro. Both autosensitization against syngeneic or allosensitization against C57BL fibroblasts augmented the lymph node response of (C3H × C57BL)F₁ hybrid recipients. The recruited or donor components of these mixed responses could be selectively abolished by irradiating either the donor lymphocytes or the recipient mice. Hence, the autosensitization response, like the host-vs.-graft transplantation reaction, can be induced by sensitization of lymphocytes peripherally and involves recruitment of lymphocytes within regional lymph nodes. The GvH response manifested in the same popliteal lymph nodes does not appear to require the recruitment of radiosensitive T lymphocytes. These findings suggest that different classes of T lymphocytes function in the autosensitization and GvH responses.     

CD3+ T-cells in severe combined immunodeficiency (scid) mice. III. Transferred congenic, selfreactive CD4+ T cell clones rescue IgM-producing, scid-derived B cells.

Young severe combined immunodeficiency (scid) mice completely lack immunocompetent lymphocytes. Limiting numbers of purified CD4+ T cells from allotype-congenic BALB/c (Igha) donor mice were transplanted into 3-week-old scid (Ighb) recipient mice. Splenic CD4+ T cells were recovered from transplanted scid mice 10-12 weeks post-transfer and established as T cell lines in culture. These T cell populations proliferated in vitro in response to syngeneic stimulator cells. T cell clones derived in vitro from these T cell lines displayed selfreactive recognition specificity: these CD4+ T cells proliferated in vitro in response to syngeneic/congeneic but not allogeneic stimulator cells. Cloned selfreactive T cells retransplanted into young scid recipients were engrafted into spleens of secondary recipients, did not induce autoimmune disease but stimulated development of scid-derived (Ighb), IgM-producing B cells (B cell leakiness).     

The relative difference in anti-Listeria resistance of C57BL/6 and A/J mice is not eliminated by active immunization or by transfer of Listeria-immune T cells.

In this study, we examined the effects of active and adoptive immunization on the anti-Listeria resistance of innately resistant C57BL/6 and innately susceptible A/J mice. Although active immunization with a sublethal dose of viable Listeria monocytogenes markedly enhanced the anti-Listeria resistance of both C57BL/6 and A/J mice, the 100-fold difference between the two strains in innate anti-Listeria resistance was not diminished. Following immunization with an equivalent sublethal dose (0.1 LD50) of L. monocytogenes, both C57BL/6 and A/J mice generated T cells that could transfer significant and comparable protection to syngeneic recipients that were challenged with up to a 10 LD50 dose of L. monocytogenes. When the absolute number of viable Listeria was compared, however, it was clear that T cells from immunized C57BL/6 mice were capable of transferring protection to syngeneic recipients at Listeria challenge doses that were more than 100-fold greater than could T cells from Listeria-immunized A/J mice. Both active immunization and adoptive transfer of syngeneic Listeria-immune T cells enhanced the accumulation of inflammatory neutrophils and macrophages in C57BL/6 and A/J mice. More inflammatory neutrophils were recovered from actively immunized C57BL/6 than from A/J mice, whereas more inflammatory macrophages were obtained from adoptively immunized C57BL/6 than from A/J mice. These results provide further evidence for the beneficial role of inflammation in genetically determined innate resistance and T-cell mediated resistance to listeriosis. These data also suggest that some mechanism in addition to inflammatory responsiveness may be responsible for limiting the expression of acquired anti-Listeria resistance in genetically susceptible A/J mice.     

The role of macrophage activation and of Bcg-encoded macrophage function(s) in the control of Mycobacterium avium infection in mice.

Following the intraperitoneal inoculation of 2.5 x 10(8) colony-forming units of Mycobacterium avium strain ATCC 25291, there was bacillary growth in the liver, spleen and peritoneal cavity of C57BL/6, C57BL/10, DBA/1 and BALB/c mice whereas DBA/2, C3H/He, CBA/Ca and CD-1 mice controlled the infection showing constant or slightly decreasing numbers of viable bacteria in the liver and spleen and effective clearance of the bacilli from the peritoneal cavities. The acquisition of non-specific resistance (NSR) to Listeria monocytogenes during the infection by M. avium was high in C57BL/6, BALB/c and C3H/He mice and negligible in DBA/2 and CD-1 mice. The magnitude of the acquisition of NSR was reduced in T cell-deficient mice and was directly proportional to the dose of the inoculum of M. avium. The production of hydrogen peroxide by phorbol myristate acetate-stimulated peritoneal macrophages of M. avium-infected mice was higher in C57BL/6 and BALB/c mice than in CD-1, DBA/2 and C3H/He animals. BALB/c. Bcgr (C.D2) mice, unlike their congenic strain BALB/c, restricted bacterial growth following the intravenous inoculation of 2.5 x 10(8) CFU of M. avium as efficiently as DBA/2 mice. C.D2 and BALB/c peritoneal macrophages from infected mice produced similar amounts of H2O2 but BALB/c mice developed higher levels of NSR to listeria than C.D2 mice. The production of nitrite by peritoneal macrophages from infected mice was found to be enhanced in DBA/2 and C3H/He but not in BALB/c, C57BL/6, DC-1 and C.D2 mice. Resident peritoneal macrophages from C.D2 mice were more bacteriostatic in vitro for M. avium than macrophages from BALB/c mice. The same relative differences between the two macrophage populations were observed when the cells were activated with lymphokines. The results show that the populations were observed when the cells were activated with lymphokines. The results show that the resistance to M. avium infection in mice is under the control of the Bcg gene and that susceptibility may be due to some defect in macrophage antibacterial function not completely overcome by the activation of this phagocyte in the susceptible strains of mice.     

Anti-receptor antibody-induced suppression of murine H-Y-specific delayed-type hypersensitivity responses

A putative anti-H-Y receptor antiserum (ARA) was raised in C57BL/6 male mice against splenic T lymphocytes from syngeneic females immunized against H-Y antigen. When this antiserum is given i.v. to C57BL/6 females it prevents the expression of H-Y-specific delayed-type hypersensitivity (DTH). The suppressive activity in ARA was selectively retained on rabbit anti-mouse immunoglobulin columns, and could be absorbed by H-Y-immune spleen cells from C57BL/6 female mice. The abrogation of H-Y DTH reactivity was at least in part due to the generation of suppressor T cells which are generated by ARA in naive female mice. ARA-generated suppressor cells specifically inhibit the induction phase of DTH responses to the H-Y antigen, having no effect on (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific cutaneous sensitivity responses or on DTH responses to minor histocompatibility antigens. Furthermore, there is a requirement for Igh gene homology between the strain producing the ARA and the strain in which the DTH response is induced. Thus, C57BL/6 ARA given to A.BY (H-2b, Igh-1e) or to B.C-8 (H-2b, Igh-1a) mice was unable to suppress homologous H-Y DTH responses in these strains. However, C57BL/6 ARA induced suppressor cells in B.C-8 mice which were capable of inhibiting H-Y DTH responses when adoptively transferred to C57BL/6 females.     

Persistence of anti-donor allohelper T cells after neonatal induction of allotolerance in mice

BALB/c mice rendered tolerant to A/J alloantigens by neonatal injection of 10(8) (A/J X BALB/c)F1 spleen cells develop an autoimmune disease associated with a polyclonal activation of donor B cells. To study the mechanisms leading to donor B cell activation in tolerant mice, we prepared mixed lymphocyte cultures (MLC) between splenic T cells from neonatally injected mice and donor-type (A/J X BALB/c)F1 or third-party (C57BL/6 X BALB/c)F1 B cells. T cells from tolerized mice were unable to generate cytotoxic T lymphocytes, to proliferate or to secrete interleukin (IL)2 after stimulation with donor alloantigens in MLC. These T cell responses were present after MLC with third-party antigens, but were of lower intensity than those generated by control BALB/c T cells. In contrast, T cells from tolerized mice stimulated immunoglobulin production by donor-type (A/J X BALB/c)F1 B cells much more powerfully than T cells from control BALB/c mice. The stimulation of donor-type (A/J X BALB/c)F1 B cells was polyclonal, as attested by the levels of anti-hapten and anti-DNA antibodies in the MLC supernatants. IgM was the dominant isotype secreted in vitro, but IgG1 and IgG3 were also produced in significant amounts. Lysis experiments indicated that the T cells responsible for F1 B cell stimulation in MLC were CD4+ host T cells. These T helper cells were alloreactive since they did not stimulate syngeneic BALB/c B cells, and their effect on donor B cells was specifically blocked by anti-donor Ia monoclonal antibodies. Addition of anti-IL 4 monoclonal antibody to MLC between T cells from tolerant mice and (A/J X BALB/c)F1 B cells almost completely abolished the production of IgG1, but not that of IgM or IgG3. Taken together, these findings indicate that neonatal injection of alloantigens in BALB/c mice induces a state of dissociated tolerance, with unresponsiveness of anti-donor T cells secreting IL 2 on the one hand, and persistence of T cells responsible for B cell help and IL 4 secretion on the other hand.     

CD4+ T cells but Not CD8+ or gammadelta+ lymphocytes are required for host protection against Mycobacterium avium infection and dissemination through the intestinal route

Disseminated Mycobacterium avium infection is common in AIDS patients that do not receive anti-AIDS therapy and in patients for whom therapy fails. M. avium is commonly acquired by ingestion, and a large number of AIDS patients have M. avium in their intestinal tracts. To better understand the dynamics of the infection in patients with AIDS, we studied orally infected mice. To determine if immunocompetent mice challenged orally with M. avium can develop protection against the infection, and if so, which cell population(s) is responsible for the protection, we exposed wild-type as well as CD4(-/-), CD8(-/-), and gammadelta(-/-) knockout mice to low concentrations of M. avium strain 101 given orally, followed by treatment with azithromycin. After 1 month, the mice were challenged with kanamycin-resistant M. avium 104. Only CD4(+) T cells appeared to be required for protection against the second challenge. Both CD4(+) and CD8(+) T cells produced comparable amounts of gamma interferon after the first exposure to the bacterium. Tumor necrosis factor alpha was elevated in CD4(+) T cells but not in CD8(+) T cells. Following exposure to a small inoculum of mycobacteria orally, wild-type mice did not develop disseminated infection for approximately 4 months, although viable bacteria could be observed in the mesenteric lymph nodes. The ingestion of small numbers of M. avium cells induces a protective immune response in the intestines against subsequent infection. However, the bacteria remain viable in intestinal lymph nodes and might disseminate later.     

T cell-dependent chronic neutrophilia during mycobacterial infections.

Euthymic (nu/+) C57BL/6 mice intraperitoneally inoculated with 2.5 x 10(6) colony-forming units (CFU) of Mycobacterium avium developed a chronic peritoneal neutrophilic granulocytosis during the 30 days of infection studied; in contrast, congenitally athymic nude (nu/nu) mice of C57BL/6 background did not show such persistent neutrophil influx. The acute phase of peritoneal infection, characterized by an extensive accumulation of neutrophils peaking at 6 to 12 h post-inoculation, was similar in euthymic and athymic mice. Subcutaneous vaccination of C57BL/6 mice with BCG enhanced the peritoneal influx of granulocytes after the i.p. inoculation of 2.5 x 10(60 CFU of M. avium. Finally, spleen cells from M. avium-infected mice pulsed in vitro with mycobacterial antigen induced a higher neutrophil accumulation after inoculation into the peritoneal cavity of naive recipient mice than unpulsed spleen cells or spleen cells from noninfected mice. These data indicate that the immune system is involved in the regulation of the chronic neutrophil influx during mycobacterial infection.     

Non-major histocompatibility complex control of antibody isotype and Th1 versus Th2 cytokines during experimental infection of mice with Mycobacterium avium

Infection of different strains of mice with Mycobacterium avium has revealed genetic control of the immunoglobulin isotype induced and of the balance between Th1 and Th2 cytokines. Female BALB/c or C57BL/10 mice were infected intranasally with 10(5) M. avium organisms. The antibody response was measured over 18 weeks by enzyme-linked immunosorbent assay and Western blotting, while numbers of cytokine-producing cells were assessed at 12 to 15 weeks by ELISPOT assay. Upon infection, C57BL/10 mice produced a clear Th1 response with strong gamma interferon (IFN-gamma) production, no interleukin-4 (IL-4), and almost entirely immunoglobulin G2a (IgG2a) antibody. In contrast, BALB/c mice developed T cells producing IL-4, as well as those producing IFN-gamma, while the antibody response was a mixture of IgG1 and IgG2a. Antibodies from BALB/c mice were also able to recognize a greater range of antigens than were C56BL/10 mice. B10D2 mice, which carry the BALB/c major histocompatibility complex haplotype on a C57BL/10 background, followed the C57BL/10 cytokine pattern. Mice infected with Listeria monocytogenes did not show a similar response dichotomy.     

Role of Macrophages in Resistance to Murine Cytomegalovirus

The role of macrophages in protecting mice from murine cytomegalovirus (MCMV) was studied in Swiss, CBA/J, and C57BL/6J mice. CBA/J mice were more resistant to virus than were C57BL/6J mice at all ages tested. Prior treatment of adult Swiss mice with 60 mg of silica, a dose selectively toxic to macrophages, increased mortality due to MCMV infection. Transfer of syngeneic adult macrophages to suckling mice significantly increased their resistance to subsequent MCMV infection. Transfer of syngeneic, nonimmune adult lymphocytes to suckling mice also had a lesser but significant protective effect against subsequent MCMV challenge. In vitro infection of adult CBA/J and C57BL/6J macrophages with virulent and attenuated MCMV resulted in productive infection in only a small percentage of cells and recovery of very little virus from the extracellular fluid. Infection of CBA macrophages was no less productive than C57BL/6J nor was infection with virulent virus more productive than with attenuated virus. Histological examination of the livers of MCMV-infected CBA/J and C57BL/6J mice suggested that divergent cellular immune responses to infection might account for differences in susceptibility. It is postulated that the macrophage may facilitate the inductive phase of cellular immunity, one possible explanation for its demonstrated importance in host defenses against MCMV.     

Loss of Aggression, After Transfer onto a C57BL/6J Background, in Mice Carrying a Targeted Disruption of the Neuronal Nitric Oxide Synthase Gene

Phenotypic differences among mice with disrupted genes and those with wild-type alleles have not provided the necessary evidence for desired gene/phenotype correlations. These differences could be due to "passenger genes" from the donor 129 strains that are used to produce stem cells. Three variations of attack behavior were measured, using mice carrying a disruption of the neural nitric oxide synthase gene. In the first population, the disrupted gene had been maintained on a mixed background including C57BL/6J and 129 alleles. We have developed a second population in which the disrupted gene was transferred onto a C57BL/6J background during five backcross generations. On the mixed C57BL/6J-129 background, mice homozygous for disrupted Nos1 alleles attacked more frequently, had shorter attack latencies, and presented a greater number of attacks than mice carrying nondisrupted alleles. On the C57BL/6J background, no significant difference persisted between the carriers of the disrupted gene and their noncarrier siblings. The noncarriers on the mixed C57BL/6J-129 background, and the carriers or noncarriers on the C57BL/6J background, did not differ from C57BL/6J. The frequency of attacking males was identical in the homozygous carriers of the disrupted gene, in the mixed C57BL/6J-129 background, and in the 129/SvPas, which approximates the 129/SvJae strain from which the stem cells were derived to produce the disrupted Nos1 gene. These results suggest that Nos1 disruption was not implicated in attack behavior. A possible passenger-gene effect from the 129 donor strain is discussed.     

The IgG antibody reactivity of sera from patients with active chronic hepatitis to a crude liver antigen and liver specific protein (LSP): analysis by ELISA and immunoblotting.

This report extends our previous study on experimental autoimmune hepatitis in C57BL/6(B6) mice. Cellular immunity involved in the induction of liver injury in this model was studied by transfer of primed spleen cells from hepatitis donor mice to syngeneic normal recipient mice. The most prominent liver damage in recipient B6 mice was induced by transfer of nylon wool adherent spleen cells from hepatitis donor mice, and T cells in this fraction were the essential requirement for the liver damage in the recipient mice. Nylon wool adherent spleen cells from hepatitis donor mice after depletion of the suppressor T-cell function by low-dose (300 rad) irradiation induced more severe liver injury compared to the same cells without irradiation. When the recipient mice were depleted of lymphocytes by low or high dose (700 rad) whole body irradiation, transfer of primed spleen cells from hepatitis donor mice did not induce liver lesion in the lymphocyte-depleted mice. This low susceptibility of lymphocyte-depleted recipient mice to primed spleen cells of hepatitis mice was no longer demonstrated after reconstitution with normal spleen cells. In a cell-migration study using 51Cr-labelled spleen cells, it was shown that a considerable number of infiltrating cells in the liver of recipient mice were derived from recipient mice themselves. These results seem to indicate that cell-to-cell interaction between radiosensitive precursor cells of recipient mice and liver-antigen-primed T cells from hepatitis donor mice play an essential role in the induction of liver injury in the recipient mice.     

Immunological status of nude mice engrafted with allogeneic or syngeneic thymuses

Restoration of T-cell functions and changes in autoantibody production were studied in BALB/c nu/nu (nude) mice engrafted with syngeneic (BALB/c) or allogeneic (C57BL/6J) thymuses across major histocompatability barriers. T-cell functions, including mitogen responses and antibody production to sheep red blood cells (SRBC), were restored in nude mice engrafted with either allogeneic or syngeneic thymuses. Alloreactivity was evaluated by analysis of the pattern of skin allograft rejection, generation of alloreactive cytotoxic T-lymphocytes (CTLs), or quantitation of mixed-lymphocyte reaction (MLR). BABL/c nude mice engrafted with thymuses from newborn C57BL/6J mice accepted the skin from either thymus donor-type mice or from host-type mice. By contrast, such thymic chimeras rejected skin grafts from a third-party donor. CTLs from nude mice engrafted with C57BL/6J thymuses were cytotoxic to target cells of the third party but not to target cells of the host-type or of the thymus-type. In the MLR assay, spleen cells of nude mice engrafted with C57BL/6J thymuses responded vigorously to third party cells and only slightly to cells of the thymus-type. Low levels of serum IgG and high titers of IgM antibodies to nuclear antigens (but not dsDNA) or skin basal cells were also found in nude mice. Antibodies to both nuclear antigens and skin basal cells disappeared after transplantation of syngeneic thymuses, but not after transplantation of allogeneic thymuses. By contrast, serum IgG levels were restored to normal in nude mice engrafted with either syngeneic or allogeneic thymuses. These results suggest that either HLA-matched or HLA-mismatched thymus grafts may become a viable treatment for certain patients with T cell deficiencies associated with deficient development or maintenance of thymic structure and/or function.     

Graft-facilitating doses of ex vivo activated gammadelta T cells do not cause lethal murine graft-vs.-host disease.

The purpose of this study was to examine the ability of gamma(delta) T cells to cause graft-vs.-host disease (GVHD) after allogeneic bone marrow transplantation (BMT) and to determine whether these cells offered any therapeutic advantages relative to alphabeta T cells. Due to the paucity of naive gamma(delta) T cells in mice and humans, gamma(delta), T cells (obtained from alpha(beta) T cell-deficient murine donors) were ex vivo activated and expanded in interleukin (IL)-2 so as to achieve sufficient cell numbers and to serve as a more clinically feasible strategy. After transplantation into lethally irradiated hosts, donor gamma(delta) T cells were detected in target organs of GVHD such as the spleen and intestines 2 weeks after BMT and constituted the primary T cell subpopulation. Large doses (150 x 10(6)) of activated gamma(delta) T cells, which we have previously shown capable of facilitating engraftment in MHC-disparate recipients, failed to cause fatal GVHD in lethally irradiated recipients of MHC-incompatible donor marrow grafts (C57BL/6 [H-2b]-->B10.BR [H-2k] and C57BL/6 [H-2b]-B6D2F1[H-2b/d]). The absence of GVHD was confirmed by histologic analysis of target organs, splenic B cell reconstitution, and appropriate negative selection in the thymus, that were all comparable to those observed in mice transplanted with T cell-depleted BM only. While early splenic reconstitution was attributable to donor gamma(delta) T cells, analysis of durably engrafted chimeras 2 months posttransplant revealed that the vast majority of donor splenic T cells expressed the alpha(beta) T cell receptor. The results of secondary adoptive transfer assays showed that these cells were tolerant of recipient alloantigens in vivo, demonstrating that gamma(delta) T cells did not prevent the subsequent development of donor anti-host tolerance in BM-derived alpha(beta) T cells. When comparatively evaluated, the minimal number of naive alpha(beta) T cells necessary for donor engraftment caused significantly more fatal GVHD than the corresponding minimal dose of activated gamma(delta) T cells and thus had a superior therapeutic index. These studies indicate that doses of activated gamma(delta) T cells that are able to promote alloengraftment do not cause lethal GVHD in mice transplanted with MHC-incompatible marrow grafts.