Heterogeneity of interleukin 1 production in cultured Reed-Sternberg cell lines HDLM-1, HDLM-1d, and KM-H2.

Interleukin 1 (IL-1) is known for its role in modulating the immune response and is required for initiation of lymphocyte proliferation by means of increased IL-2 production by lymphocytes. Previously, the expression of IL-1 in H-RS cells in tissue sections was shown by using immunoperoxidase staining. For further confirmation, the production of IL-1 in cultured cells of the H-RS cell lines HDLM-1, HDLM-1d, and KM-H2 was examined by using a murine D10.G4.1 T cell proliferation bioassay and Northern blot hybridization with specific IL-1 cDNA probes. It was confirmed that two types of H-RS cells, HDLM-1 and KM-H2, can secrete IL-1, especially after treatment with phorbol ester. The amounts of IL-1 in H-RS cell culture medium ranged from approximately 0.5 to 2.5 ng/ml. The major IL-1 secreted by HDLM-1 cells was IL-1 alpha, and by KM-H2 cells was IL-1 beta. HDLM-1d cells did not produce IL-1. This finding indicates the heterogeneity of IL-1 production in H-RS cells. Such heterogeneity may apply to H-RS cells in vivo, based on the variable IL-1 staining of these cells in lymphoid tissues.     

Human dendritic cells stimulate allogeneic T cells in the absence of IL-1

Dendritic cells (DC), which express high-density HLA class II molecules, stimulate strong primary allogeneic T-cell responses via an interaction of the T-cell receptor with major histocompatibility complex (MHC) antigens (signal 1). It is not yet clear whether they also provide a second stimulus to the responding T cell in the form of the cytokine interleukin-1 (IL-1). To clarify this point, the ability of purified human tonsil DC to produce IL-1 and to stimulate allogeneic T cells was tested. No intracellular IL-1 alpha or beta was identified in DC comparable to that readily demonstrated in monocytes, and IL-1 release from lipopolysaccharide (LPS)-stimulated DC was not detected in either a biological assay for IL-1 or an ELISA assay for IL-1 beta. Furthermore, strong stimulation of allogeneic T lymphocytes by DC in the mixed leucocyte reaction (MLR) was noted to occur in the absence of IL-1 production, and this stimulation was not inhibited by polyclonal antisera to IL-1 alpha and IL-1 beta, which were known to inhibit IL-1-mediated thymocyte proliferation. Other HLA-class II-positive cell populations, namely peripheral blood monocytes and B cells, purified by methods which avoided DC contamination, were unable to stimulate allogeneic T cells with or without supplementary IL-1. We conclude that DC are very effective stimulators of T lymphocytes and that IL-1 is not required as a second signal for allogeneic T-cell responses.     

Lymphocyte functional antigens stabilize agglutination between Reed-Sternberg cells and T cells, but are not responsible for homotypic binding of Hodgkin's Reed-Sternberg cells.

The neoplastic (Hodgkin's Reed-Sternberg [H-RS]) cells in Hodgkin's disease (HD) are known for their unique capacity to form rosettes with unprimed T cells. Recently, a family of leukocyte-adherence molecules (LFA-1 and LFA-2) has been identified on T lymphocytes. The molecules bind to intercellular-adhesion molecules (ICAMs) and to LFA-3, respectively, which are associated with antigen-presenting cells. In this study, the authors examined whether these molecules are responsible for the homotypic and heterotypic agglutination that occurs in the cultured H-RS cells HDLM-1, HDLM-1d, and KM-H2. Despite their similar expressions of LFA-3 and ICAM-1, the different H-RS cells tested showed different growth patterns in culture. HDLM-1 cells grew singly, whereas HDLM-1d and KM-H2 cells grew in clumps. The HDLM-1 cells formed clumps when mixed with peripheral-blood T lymphocytes, cells of two lymphoblastic T-cell lines (MOLT-3 and MOLT-4), and cells of two monocyte lines (ML-1 and U-937). The addition of anti-LFA and ICAM-1 antibodies to cultures did not result in disassembly of the homotypic clusters of HDLM-1d or KM-H2 cells and it did not cause any significant changes in the size of heterotypic clusters or in the timing of cluster formation of HDLM-1 cells with other types of cells. In all studies, the cell clusters formed during homotypic and heterotypic aggregation were disassembled only minimally by cell shearing with pipetting. The disaggregation by pipetting was slightly more prominent in the presence of antibodies than was that of control cultures. However, in no case did the use of monoclonal antibodies (MAbs) and cell shearing cause complete disaggregation of homotypic and heterotypic clusters. The result seems to suggest that binding between H-RS cells and T cells and between H-RS cells and monocytes is not mediated primarily by LFAs and ICAMs, but that the binding may be strengthened in the presence of these molecules.     

T cell blast stimulation of MLR: role of interleukin 1 and interleukin 2.

T cells blasts were examined for the ability to stimulate primary mixed leucocyte reactions (MLR) in the presence or absence of supplemental interleukin 1 (IL-1) or interleukin 2 (IL-2). After purification, resting T cells were activated using monoclonal anti-CD3 antibody in an accessory-cell free systems. After irradiation, such cells were found to be non-stimulatory in autologous or allogeneic MLR except in the presence of supplemental IL-2. IL-1 was an ineffective cofactor, despite its ability to enhance anti-CD3 mediated stimulation of T cells. It is concluded that T cell blasts may lack an essential factor needed to stimulate IL-2 secretion (other than IL-1), or may elicit responses only from allogeneic T cells not bearing IL-1 receptors.     

Both Dendritic Cells and Monocytes Induce Autologous and Allogeneic T Cells Receptive to Interleukin 2

Activation of resting T cells to proliferate is usually accompanied by their expression of interleukin 2 receptors (IL-2R) and secretion of (IL-2). We studied the mechanisms by which human blood-derived dendritic cells (DC) and monocytes induce IL-2R and stimulate IL-2 secretion in autologous and allogeneic mixed luecocyte reaction (auto- and allo-MLR, respectively). We found that only DC were fully effective as stimulator cells in MLR. DC stimulated both autologous and allogeneic T cells to express high-affinity IL-2R, secrete IL-2, and vigorously proliferate in MLR. The stimulatory properties of monocytes were more complicated: although they stimulated the proliferation in allogeneic MLR, the proliferation rates, duration, and amount of IL-2 secretion were different than in DC-induced MLR. Autologous T cells did not proliferate in response to monocytes, but were induced to express the low-affinity IL-2R. If the cultures were supplemented with exogenous recombinant IL-2, the proliferative responses to DC and monocytes in auto- and allo-MLR were of the same magnitude, indicating that the responsiveness to IL-2 was stimulated by both the stimulator cells. The stimulator cell number was important, since large numbers of monocytes, but not of DC, were suppressive to the proliferative responses. Thus, we concluded that the higher capacity of DC, as compared to monocytes, to stimulate T-cell proliferation is based primarily on the more efficient stimulation of IL-2 secretion.     

调节性DC分泌的外体诱导免疫耐受功能的体外研究

为了探讨树突状细胞(DC)分泌的外体(Dex)在诱导T细胞免疫耐受中的作用,体外研究采用供体Dex降低同种异体移植排斥的可能性。从正常人外周血单个核细胞中诱导培养未成熟DC(imDC),用TGF-β1联合IL-10诱导调节性DC,LPS诱导DC成熟。采用流式细胞术方法观察TGF-β1和IL-10对DC表型、吞噬功能的影响;采用超速离心和超滤的方法提纯Dex;Western blot方法检测imDC分泌的Dex(imDex)与调节性DC分泌的Dex(rDex)表达的相关分子;通过CCK-8法分析异源iDex和mDex在混合淋巴细胞反应(MLR)中的生物学功能,并比较rDex与iDex诱导免疫耐受的能力。结果显示,TGF-β1和IL-10可下调DC表面的共刺激分子CD80、CD83、CD86的表达,并诱导调节性DC分泌更多的rDex;异源的mDC分泌的Dex(mDex)在mDC存在时增强MLR,而异源的imDex在imDC存在时一定程度上抑制MLR,rDex诱导的抑制T细胞增殖作用显著强于iDex;rDex表达更多的FasL,提示TGF-β1和IL-10诱导的调节性DC分泌的rDex在免疫耐受中发挥重要作用,有望应用于同种异体移植抗免疫排斥。     

Combined cyclosporin-A /prednisone therapy of patients with active uveitis suppresses IFN-gamma production and the function of dendritic cells

In this study, we assessed the Th1/Th2 polarization of the immune response and the involvement of dendritic cells (DC) and Th1 lymphocytes in the pathogenesis of uveitis. Thirty-seven patients with chronic idiopathic uveitis were enrolled: 21 of them had active uveitis and the remaining 16 were in complete remission. Patients with active uveitis were characterized as follows: 5 had intermediate uveitis, 5 panuveitis and the remaining 11 posterior uveitis. Thirteen healthy subjects were also studied as controls. Patients with active uveitis were treated with cyclosporin-A (CsA) associated to low doses of prednisone (PDS) and studied at baseline and after 6 months of therapy. Analysis of cytokine-producing CD3+ lymphocytes revealed a strong Th1 polarization of the immune response in patients with active uveitis. Th1 lymphocytes paralleled serum IL-12 levels and the response to therapy, which greatly reduced both IFN-gamma+/CD3+ lymphocytes and serum IL-12 levels, associated with a general clinical improvement. In vitro studies demonstrated that DC from untreated patients with active uveitis were mature and functionally active. In fact, they showed a higher ability to stimulate cell proliferation of allogeneic T cells in primary mixed lymphocyte reaction (MLR) and produced larger amounts of IL-12 than DC from CsA/PDS-treated patients and those in remission. These results demonstrate that CsA/PDS therapy impairs the capacity of mature DC to secrete IL-12 and inhibits their MLR activity.     

Human natural killer cells enhance a mixed leukocyte reaction

Natural killer cells (NK) have been reported to down-regulate the initiation of T cell responses in animal models. In the current study, highly purified CD16+ human NK cells were obtained by cell sorting and their effect on the stimulation of allogeneic T cells (MLR) determined. NK cells did not directly stimulate T cell proliferation. However, when added to a population of loosely adherent mononuclear cells (LAM), NK enhanced the ability of these accessory cells to stimulate T proliferation. This effect was not reproduced by the addition of sorted CD5 + T cells, sorted CD16- cells, or control lymphocytes to the MLR. The effect of NK on the MLR was not restricted by class II antigens and was similar to the effect of adding IL-1 to MLR cultures. These results demonstrate that human NK cells are capable of enhancing a T cell response.     

MHC class II molecules transferred between allogeneic dendritic cells stimulate primary mixed leukocyte reactions.

Presentation of antigen to T cells is generally restricted by MHC type but the mixed leukocyte reaction (MLR) was thought to involve direct stimulation by dendritic cells (DC) of allogeneic T cells. However, here we showed that DC bearing allogeneic MHC class II acted synergistically with responder-type DC. Removal of residual DC from 'purified' responder T cell populations was achieved using treatment with DC-specific antibody and complement. These DC-depleted cells showed a significantly reduced response to allogeneic DC which was restored by addition of DC syngeneic with responder T cells. The studies support the concept that a major component of the MLR is the secondary presentation of alloantigens acquired from stimulator DC by DC of responder type. To investigate the reasons why DC and not other cells stimulate an MLR, synergy between DC and other cell types was investigated. Synergy was found exclusively between DC; macrophages, B cells or L cells transfected with MHC class II molecules did not contribute. When allogeneic DC were mixed in culture, transfer of MHC molecules between DC was observed as assessed by flow cytometry. Freshly obtained cell-free supernatants from cultured DC contained MHC class II and stimulated primary allogeneic MLR. DC of responder type acquired allogeneic MHC molecules from the supernatants and stimulated proliferation in syngeneic T cells. The capacity of DC both to shed and to acquire MHC molecules may contribute to their potency in stimulating primary responses, and could explain why passenger DC within allografts provide a potent stimulus for graft rejection.     

Production of tumor necrosis factor-alpha and lymphotoxin by cells of Hodgkin''s neoplastic cell lines HDLM-1 and KM-H2.

The production of tumor necrosis factors (TNF) from cells of two Hodgkin's Reed-Sternberg (H-RS) lines, HDLM-1 and KM-H2 was examined. The culture supernatant from these two types of H-RS cells exerts a cytotoxic effect on L929 cells. Both tumor necrosis factor (TNF-alpha) and lymphotoxin (TNF-beta) are responsible for this activity. This was confirmed by the presence in the cells of proteins and m-RNAs of TNF-alpha and TNF-beta, as determined with immunoperoxidase staining and Northern blot hybridization. Approximately 20% of HDLM cells and 5% of KM-H2 cells were positively stained by a monoclonal anti-TNF-alpha antibody, and this staining was inhibited by preabsorption of the antibody with recombinant TNF-alpha. Staining with anti-TNF-beta, however, showed an intense reaction in more than 60% of HDLM-1 cells, but only in 5% to 10% of KM-H2 cells. The abundant expression of TNF-beta in HDLM-1 cells is consistent with approximately 10 times the TNF activity in HDLM-1-conditioned medium as compared with that of KM-H2. The rich secretion of TNF-beta in HDLM-1 cells was also validated by the inhibition of most of the TNF activity in HDLM-1-conditioned medium with anti-TNF-beta antibody, and by the presence of abundant TNF-beta mRNA in HDLM-1 cells. The reason for the abundant production of TNF-beta in HDLM-1 cells is not yet known, but may be attributable to a chromosomal abnormality in the 6p21 region. The expression of TNF-alpha, but not TNF-beta, by H-RS cells was demonstrated in lymph nodes from patients with Hodgkin's disease. The capacity of H-RS cells to secrete TNF as well as other cytokines, such as interleukin-1, colony-stimulating factors, and transforming growth factors, may contribute to the unique clinical and histopathologic alterations in patients with Hodgkin's disease.     

Human dendritic cells activate T lymphocytes via a CD40: CD40 ligand-dependent pathway

The CD40: CD40 ligand (CD40L) interaction provides T lymphocyte-mediated help for B lymphocyte and monocyte function but has also been shown to serve as a co-stimulus for T lymphocyte activation. In this report, we studied the regulation of CD40 expression and its functional relevance for the human dendritic cell (DC) stimulation of T lymphocytes. Only a small subpopulation of directly isolated blood DC expressed CD40. However, CD40 was rapidly up-regulated by culture, and its expression was further enhanced by interleukin (IL)-1α, IL-1β, IL-3, tumor necrosis factor-α and granulocyte/macrophage-colony-stimulating factor. Expression of CD40L on DC was not detected. The proliferation of T lymphocytes in an allogeneic mixed leukocyte reaction, stimulated by blood DC or epidermal Langerhans cells, was significantly reduced in the presence of the CD40 immunoglobulin (CD40Ig) fusion protein or CD40L monoclonal antibodies. Cross-linking of CD40 on directly isolated DC with mouse CD40L trimer (mCD40LT) markedly augmented CD80 and CD86 up-regulation. Nevertheless, the same cross-linking mCD40LT inhibited DC stimulated T lymphocyte proliferation. When CD40Ig was added simultaneously with CTLA-4Ig, only minimal and variable additional inhibition of DC-stimulated allogeneic T lymphocyte proliferation and IL-2 secretion was observed, compared to each fusion protein alone. These results suggest that both CD80/CD86-dependent and -independent components of DC-T lymphocyte CD40: CD40L co-stimulation exist and further emphasize that the majority of blood DC have to differentiate or be activated to express co-stimulatory molecules.     

Dendritic cells and HIV infection; immunity with viral transmission versus compromised cellular immunity?

In this commentary we propose that changes in immune activity in HIV1 infection are secondary to two aspects of the function of dendritic antigen presenting cells (DC). Firstly DC initiate primary proliferative and cytotoxic T cell responses to HIV but disseminate virus to T cells. Secondly, balanced against the development of protective immunity is progressive inhibition of the capacity of DC to initiate primary T cell responses. With regard to viral transmission via DC, recent studies provide direct evidence that virus has evolved in vivo by passage between DC and T cells and that DC can act as a reservoir for virus. Thus, phylogenetic trees of the sequences of V3 loops of HIV viruses in individual blood samples show evolution via DC and T cells, and plasma virus can be related preferentially to that derived from DC. In functional studies, DC from asymptomatic individuals (lacking lymphadenopathy and without treatment) cause low levels of stimulation of allogeneic lymphocytes in the mixed leukocyte reaction (MLR). By contrast, lymphocytes from these patients respond to normal allogeneic DC. Our recent evidence shows that DC stimulate an MLR by transfer of alloantigens to DC of the responder type with subsequent syngeneic stimulation of T cells. The failure of T cell stimulation by DC in HIV infection therefore shows an incapacity of these DC to transfer antigenic signals to other DC but DC that acquire and present antigen directly to stimulate T cells are still functional. The latter situation provides encouragement that immunotherapy via DC may be feasible. However, DC from HIV infected individuals promote antibody production in B cells suggesting that the initial interaction of HIV with DC produces autocrine effects on DC populations that promote interaction with B cells rather than with Tcells. Treatment that pushes the DC back towards stimulating Tcells, despite increased viral dissemination, may promote protective immunity.     

High precursor frequency of human T cells reactive to HLA-DQ molecules expressed on mouse L cell transfectants.

In humans, the HLA-DR molecule is a major stimulatory molecule of allogeneic mixed lymphocyte reactions (MLR) and a major restriction molecule for the presentation of soluble antigens to the T cell. Little is known of the biological function of HLA-DQ. To examine the size of the repertoire of precursor T cells recognizing the autologous or allogeneic HLA-DQ molecule, the frequency of T cells reactive to HLA-DQ was estimated in comparison with T cells reactive to HLA-DR. We made use of a limiting dilution analysis and mouse L cells transfectants expressing the HLA-DR or -DQ molecule, as stimulators. Human T cells recovered from a primary MLR stimulated with allogeneic peripheral blood lymphocytes (PBL) proliferated in response to L cell transfectants expressing HLA class II genes shared by the stimulator cells in the primary MLR. This observation suggested that the HLA class II molecules on L cell transfectants shared to some extent epitopes for alloreactive T cells with those expressed on human PBL. The precursor frequencies of CD4+ T cells reactive to allogeneic or autologous DQ molecules were as high as those of T cells reactive to allogeneic DR molecules and were estimated to be 1/800-1/1800. The frequency of the T cells reactive to autologous DR molecules was low (1/7200-1/16,000). The biological significance of the high frequency of HLA-DQ-reactive precursor T cells is discussed.     

Expression of p55 (Tac) interleukin-2 receptor (IL-2R), but not p75 IL-2R, in cultured H-RS cells and H-RS cells in tissues.

The authors studied the secretion of interleukin-2 (IL-2), the expression of interleukin-2 receptors (IL-2R; p55/Tac and p75), and the response to exogenous IL-2 by cultured Hodgkin's Reed-Sternberg cells (cell lines HDLM-1, HDLM-1d, and KM-H2) and T cells (H9, HuT78, HuT102, MOLT-4, and MT-2). All of these cells did not produce IL-2 or produced it in undetectable amounts, and their growth was not affected by the addition of anti-IL-2 or anti-IL-2R antibodies. This indicates that H-RS cells in long-term culture, as well as T cells, can grow independently of IL-2. The three H-RS cell lines, as well as two of the T-cell lines (HuT102 and MT-2), expressed Tac, whereas the other three T-cell lines were Tac negative. Expression of p75 was noted in the two Tac-positive T-cell lines, but not in cultured H-RS cells. The expression of Tac and p75 in HuT102 and MT-2 cells correlated well with their capacity to proliferate on treatment with exogenous IL-2. On IL-2 treatment, nucleic-acid uptake in Tac/p75-positive T cells increased approximately four- to sixfold, whereas the Tac/p75-negative T cells did not show increased proliferation. Unlike the T cells, the Tac-positive H-RS cells did not respond to IL-2. The lack of a proliferative response to IL-2 appears to be related to the absence of p75 in H-RS cells. A similar pattern (Tac positivity and p75 negativity) was noted in H-RS cells in lymph nodes involved by Hodgkin's disease. Thus the exogenous IL-2 released by surrounding T lymphocytes may not cause the proliferative activity of H-RS cells because of the lack of high-affinity IL-2 receptors in the latter cells. In contrast to H-RS cells in culture, H-RS cells in tissues were stained by a specific anti-IL-2 monoclonal antibody. This indicates that the expression of IL-2 or an IL-2-like substance by H-RS cells in tissues may be responsible, in part, for the great increase in the number of reactive T lymphocytes in tissues involved by Hodgkin's disease.     

Interleukin-1-like activity constitutively generated by Hodgkin derived cell lines. I. Measurement in a human lymphocyte co-stimulator assay

Culture supernatants (CS) from Hodgkin derived cell lines have previously been shown to contain colony stimulating activity (CSF) for human cord blood cells, fetal bone marrow and fetal liver cells. In this study 3-day CS from four Hodgkin lines (L428, L538, L540, L591) and two sublines (L428KS, L428KSA) were examined for interleukin (IL) activity. None of the tested CS supported the growth of an IL-2 dependent murine T-cell line, suggesting that the Hodgkin lines do not produce significant amounts of IL-2. When crude 3-day CS from the various lines were assayed for IL-1-activity in the conventional murine thymocyte costimulator assay no or only borderline IL-1-activity was detectable. However, concentrated CS from L428KS exhibited IL-1-activity also in this assay as did lipopolysaccharide (LPS) induced human IL-1. Surprisingly, crude 3-day CS from all Hodgkin cell lines were capable of fully replacing the accessory cell requirement in ConA-induced lymphoproliferation assays of heavily monocyte-depleted human blood lymphocytes. The monocyte-depleted lymphocyte populations were obtained by 1 X g sedimentation at a sedimentation rate of 30.2 to 38.8 mm/hr (fraction IIIa and IIIb). These cells responded poorly to the T-cell mitogen ConA at 10 micrograms/ml and produced no IL-2. Addition of irradiated, autologous monocytes or of CS from the various Hodgkin cell lines quantitatively restored the ConA responsiveness and induced significant IL-2 production in the monocyte-depleted lymphocyte population, suggesting that Hodgkin lines constitutively secrete IL-1 or IL-1-like activity. A preliminary biochemical characterization (heat and pH stability, molecular weight range of 13-24 KD) supports the notion that the accessory cell replacing activity present in CS of Hodgkin cell lines is a type of human IL-1.     

Immunoregulatory Factor Released From a Cell Line Derived From Human Decidual Tissue

ABSTRACT: The culture supernatant of the TTK-1 cell line, established from human decidual tissue, was found to contain a factor that strongly suppressed the mixed lymphocyte reaction (MLR). The mechanism of the MLR-suppressive activity as well as the biochemical characterization of this factor was analyzed. The TTK-1 supernatant suppressed the MLR much more strongly than the culture supernatants of the three other malignant cell lines examined. The molecular weight of this factor was estimated to be between 43 kilodaltons (kd) and 67 kd by gel filtration chromatography. The TTK-1 supernatant also suppressed the proliferation of the interleukin 2 (IL-2)-dependent T cell lines, but did not suppress that of the IL-2-independent T cell lines, suggesting that the TTK-1 supernatant inhibited the action of IL-2 and subsequently suppressed the MLR. The fact that the TTK-1 cell line originated from human decidual tissue might imply the important role of this factor in immunological fetomaternal balance.     

粒细胞集落刺激因子诱导的供者外周血中两种不同亚群树突状细胞免疫生物学特性的研究

目的 从粒细胞集落刺激因子(G-CSF)诱导的供者外周血中分离出CD1c+的髓细胞性DC(MDC)、CD304+类浆细胞样DC(PDC)两类DC亚群,并对其生物学特性进行分析和研究.方法 免疫磁珠法分离出MDC、PDC,分别用TNF-α、CpG2006OND诱导成熟,检测各DC亚群的表型、对同种异基因淋巴细胞的刺激反应.结果 分选的DC纯度均＞95%,MDC表达HLA-DR、CD11c、CD33、CD4,PDC表达HLA-DR、CD4、CD45RA,诱导成熟的两类DC的CD40、CD80表达均明显增高;混合淋巴细胞反应(MLR)显示:MDC具有很强的刺激淋巴细胞增殖能力,PDC刺激能力很弱;各组上清液中IFN-r均增加,MDC、mMDC组增高最为明显;PDC、mPDC刺激组上清液中IL-10明显增高;MDC、mMDC刺激后,胞浆内表达IFN-r的CD4+T细胞均明显增高;PDC、mPDC有上调CIM+CD25high调节性T细胞(Treg)作用;Foxp3 mRNA的表达在各组间无明显的差异.结论 采集的供者外周血中两类DC亚群虽然HLA-DR高表达,但仍处于非成熟状态,在合适的条件下分化成熟;无论MDC成熟与否均表现出很强的刺激T细胞增殖能力,使T细胞分泌IFN-r增加,其分泌的增加可能是促进向TH1极化的结果.PDC可能并不像MDC一样有效地捕获、处理和负载抗原到MHC分子上,因此提呈抗原效率低,表现出对T细胞的弱刺激增殖特性;PDC虽然也可以促进T细胞分泌IFN-r,但似乎并非是通过TH1细胞;PDC并不能促进TH2类因子IL-4的分泌,对TH2的极化作用可能表现在IL-10的分泌上;PDC有诱导CD4+CD25highTreg的作用.     

Hodgkin's reed-sternberg cell line (KM-H2) promotes a bidirectional differentiation of CD4+CD25+Foxp3+ T cells and CD4+ cytotoxic T lymphocytes from CD4+ naive T cells

A recent report revealed that a large population of Hodgkin's lymphoma-infiltrating lymphocytes (HLILs) consisted of regulatory T cells. In this study, we cocultured CD4+ naive T cells with KM-H2, which was established as a Hodgkin's Reed-Sternberg cell line, to clarify their ability to induce CD25+ Forkhead box P3+ (Foxp3+) T cells. The characteristic analyses of T cells cocultured with KM-H2 revealed the presence of CD4+CD25+ T cells. They expressed CTLA-4, glucocorticoid-induced TNFR family-related gene, and Foxp3 and could produce large amounts of IL-10. Conversely, KM-H2 also generated CD4+ CTLs, which expressed Granzyme B and T cell intracellular antigen-1 in addition to Foxp3+ T cells. They exhibit a strong cytotoxic effect against the parental KM-H2. In conclusion, KM-H2 promotes a bidirectional differentiation of CD4+ naive T cells toward Foxp3+ T cells and CD4+ CTLs. In addition to KM-H2, several cell lines that exhibit the APC function were able to generate Foxp3+ T cells and CD4+ CTLs. Conversely, the APC nonfunctioning cell lines examined did not induce both types of cells. Our findings suggest that the APC function of tumor cells is essential for the differentiation of CD4+ naive T cells into CD25+Foxp3+ T cells and CD4+ CTLs and at least partly explains the predominance of CD25+Foxp3+ T cells in HLILs and their contribution to a better prognosis. Therefore, in APC-functioning tumors, including classical Hodgkin lymphomas, which generate Foxp3+ T cells and CD4+ CTLs, these T cell repertories play a beneficial role synergistically in disease stability.     

Failure of TGF β1 and IL-12 to regulate human FasL and mTNF alloreactive cytotoxic T-cell pathways

Abstract: The effect of TGFβ1 and IL-12 on calcium-independent cytotoxic pathways was investigated. We have previously demonstrated that the regulatory effect of TGFβ1 and IL-12 on human alloreative CTL activity was associated with regulation of perform and granzyme B gene expression. To determine the effect of both cytokines on the alternative cytotoxic pathway involving FasL and mTNF, we first investigated the expression of both molecules on human primary alloactivated T cells. Our results show that human allostimulated T lymphocytes express FasL. Cell lysis experiments demonstrate that the FasL cytotoxic pathway is involved in the killing of specific target cells mediated by human alloreactive CTL. In addition, allogeneic stimulation induced significant mTNF expression on both CD4+ and CD8+ responder T cells. Using TNF-sensitive target cells, we also demonstrate that the mTNF-mediated cytotoxic pathway is involved in the cytotoxic activity of human primary allostimulated T lymphocytes. Neither TGFβ1 nor IL-12 had an effect on FasL or mTNF expression. Furthermore, addition of TGFβ1 or IL-12 at the initiation of the MLR had no significant effect on Fas- and mTNF-mediated cytotoxicity.
Taken together, our results provide a novel insight into the differences between regulation by cytokines of perforin-dependent and -independent cytotoxic mechanisms. Unlike their role in the perforin/granzyme B pathway, TGFβ1 and IL-12 do not appear to mediate any regulatory effect on FasL and mTNF cytotoxic pathways used by human alloreactive primary CTL.     

Generation and characterisation of bovine antigen-specific T cell lines.

15 antigen-specific T cell lines have been generated from eight individual cattle immunised with ovalbumin. Several sources of interleukin-2 (IL-2) were used, including a supernatant from a gibbon cell line (MLA-Sup), human recombinant IL-2 (hrIL-2) and bovine recombinant IL-2 (brIL-2). These IL-2 sources were used alternately with autologous peripheral blood mononuclear cells (PBM) together with ovalbumin to generate the lines. They grew least well in MLA-Sup and best in brIL-2. FACS analysis indicated that the lines generated with the recombinant IL-2s were extremely homogeneous in that the majority of cells were BoCD4+ (bovine CD4 equivalent) and therefore of TH phenotype. The lines were antigen specific and responded to antigen only in the presence of autologous PBM and not allogeneic (MHC class I nonidentical) PBM. However, allogeneic PBM did support their proliferation to ConA. No MLR response was observed by the cell lines to allogeneic PBM. The response to antigen was inhibited by anti bovine class II mAbs but not an anti bovine class I mAb. The subpopulation of PBM which acted as antigen presenting cells for these bovine TH cell lines had typical macrophage characteristics.