Characterization of a rat monoclonal antibody specific for a determinant encoded by the V beta 7 gene segment. Depletion of V beta 7+ T cells in mice with Mls-1a haplotype

We have generated a rat mAb, TR310, which recognizes a determinant encoded by the murine V beta 7 gene segment of the TCR. TR310 immunoprecipitates TCR from cell lysates, co-modulates with CD3, and can be used for immunofluorescence staining of T cells. By using this antibody, we found that the average percentage of V beta 7+ peripheral T cells in Mls-1b mice was 3.8%, but only 0.8% in Mls-1a mice. A similar difference was also observed in the mature TCRhi thymocyte subsets, suggesting that V beta 7+ T cells are deleted during intrathymic maturation in Mls-1a mice. TR310 should prove to be a valuable reagent in further studies of the TCR repertoire and the analysis of factors which alter it.

Maternally transmitted histocompatibility antigen of mice: a hydrophobic peptide of a mitochondrially encoded protein

MTF, a murine minor histocompatibility antigen, is maternally inherited and thought to be encoded by a mitochondrial gene. We sequenced the entire mitochondrial genomes from three strains that differ in MTF Mtf beta, Mtf gamma, and Mtf delta) and compared the sequences with the known, Mtf alpha, mitochondrial DNA sequence. We found only one site where all four genomes differed, affecting amino acid residue 6 of ND1, a subunit of NADH dehydrogenase. Incubation of non-Mtf alpha target cells with synthetic peptide ND1 alpha 1-17 (the first 17 amino acid of the ND1 protein of Mtf alpha mice) rendered them susceptible to lysis by MTF alpha-specific cytotoxic T cells (CTLs). Similarly, non-Mtf beta target cells were lysed by MTF beta-specific CTLs after incubation with the allelic form ND1 beta 1-17. Thus, Mtf is attributable to allelic variation at a single residue of the ND1 protein. Cells can therefore display peptides derived from mitochondrially encoded proteins, and such peptides can be histocompatibility antigens.

Altered expression of self-reactive T cell receptor V beta regions in autoimmune mice

Intrathymic tolerance results in elimination of T cells bearing self-reactive TCR V beta regions in mice expressing certain combinations of I-E and minor lymphocyte stimulatory (Mls) phenotypes. To determine if autoimmune strains of mice have a defect in intrathymic deletion of self-reactive TCR V beta regions, expression of V beta 3, V beta 6, V beta 8.1, and V beta 11 were examined in lpr/lpr and +/+ strains of mice; MRL/MpJ(H-2K, I-E+, Mlsb,), C57BL/6J(H-2b, I-E-, Mlsb,), C3H/HeJ(H-2k, I-E+, Mlsc), AKR/J(H-2k, I-E+, Mlsa); and in autoimmune NZB/N(H-2d, I-E+, Mlsa) and BXSB(H-2b, I-E-, Mlsb) mice. The results suggest that, during intrathymic development, self-reactive T cells are deleted in autoimmune strains of mice as found in normal control strains of mice. However, the TCR V beta repertoire is skewed in autoimmune strains compared to normal strains of mice. For example, MRL-lpr/lpr mice, but not other lpr/lpr strains, had increased expression of V beta 6 relative to expression in control MRL(-)+/+ mice, which is associated with collagen-induced arthritis. These data are consistent with a model of normal affinity for negative selection of self-reactive T cells in the thymus of autoimmune strains of mice followed by expansion of autoreactive T cell clones in the peripheral lymphoid organs. The peripheral lymphoid organs of lpr/lpr mice contain an expanded population of abnormal CD4-, CD8-, 6B2+ T cells. Elimination of self-reactive peripheral T cells suggests that these abnormal cells are derived from a CD4+ subpopulation in the thymus. Flow cytometry analysis of peripheral lymph node T cells from MRL-lpr/lpr mice reveal three populations of CD4+ T cells expressing low, intermediate and high intensity of B220 (6B2). This supports the hypothesis that in lpr/lpr mice, self-reactive CD4+ T cells are eliminated in the thymus, and that these cells lose expression of CD4 and acquire expression of 6B2 in the periphery.

An exact comparison between the efficiency of two- and three-cell-type clusters in mediating helper activity

Adoptive transfer of anti-H-2Db-primed B cells combined with anti-minor histocompatibility antigen-primed T cells enables the effect of linked and unlinked alloantigen to be compared. Over an extensive dose range the unlinked antigen proved ineffective. In a previously described, exactly comparable system for assessing the same effect on cytotoxic T cell precursors, low doses of linked antigen had proved approximately equally effective, but high doses of unlinked antigen had proved effective. This contrast supports the hypothesis that whereas T-B collaboration is mediated by two-cell-type clusters, collaboration between T cells requires formation of three-cell-type clusters.

Immunogenic Ia-binding peptides immobilize the Ia molecule and facilitate its aggregation on the B cell membrane. Control by the M1s-1 gene

Aggregation (e.g., through cross-linkage) of cell surface molecules is in various biologic systems a necessary event in cellular activation. Examining the Ia molecule on B cells we found that aggregation is a function of the surface Ag mobility; the higher the fraction of immobile molecules on the plane of the membrane, the better Ia forms aggregates and patches. We identify two factors that control Ia mobility and aggregability. One factor is the M1s-1a gene product; the other factor is an Ia-reactive immunogenic peptide. Both factors increase Ia aggregability and reduce the MHC Ag mobility.

Importance of suppressor T cells in cyclophosphamide-induced tolerance to the non-H-2-encoded alloantigens. Is mixed chimerism really required in maintaining a skin allograft tolerance?

Mechanisms of cyclophosphamide (CP)-induced tolerance were studied. When AKR/J Sea (AKR: H-2k) mice were primed i.v. with 5 x 10(7) spleen cells plus 1 x 10(7) bone marrow cells from [C57BL/6 Slc (B6; H-2b) x C3H/He Slc (C3H; H-2k)]F1 (B6C3F1) mice and treated i.p. with 200 mg/kg CP 2 days later, the survival of C3H skin was moderately prolonged, but the survival of either B6 or B6C3F1 skin was not prolonged. By this treatment, however, mixed chimerism of B6C3F1 cells in the AKR mice was not established. When C3H cells were used as the tolerogen, a minimal degree of mixed chimerism associated with profound tolerance to C3H skin was established. Similar results were observed in various donor-recipient combinations. When C3H skin was grafted in the AKR mice 12 wk after the treatment with C3H cells and CP, or B6C3F1 cells and CP, survival of the grafted C3H skin was prolonged remarkably or moderately, respectively, although mixed chimerism was not detectable at the timing of grafting in either of the groups. In this late stage of tolerance, a strong level of tolerogen-specific suppressor cell activity was observed in those tolerant AKR mice. The suppressor activity was mainly attributable to T cells. These results suggest that the role of Ts cells in order to maintain skin tolerance is important in our CP-induced tolerance system, especially in the late stage of tolerance. Moreover, the generation of the Ts cells does not necessarily require the establishment of a long term mixed chimeric state.

Deletion of self-reactive T cells in nude mice grafted with neonatal allogeneic thymus

The cellular basis of tolerance induction has been investigated in BALB/c(H-2d, thy 1.2, M1s1b2a) nude mice grafted with thymus of neonatal AKR/J mice(H-2k,Thy1.1,M1s1a2b). The spleen cells from nude mice grafted with AKR/J thymus showed a significantly decreased level of primary cytotoxic T cell response when stimulated with AKR/J cells, although these cells lysed well target cells of a third party C57BL/6 when stimulated with C57BL/6 cells. Consistent with CTL responses, T cells bearing V beta 6, that is important for recognizing M1s1a-encoded products of the thymic phenotype, were virtually abolished in the spleen and lymph node cells of nude mice 8 wk after grafting with AKR/J thymus. However, a substantial number of V beta 6-bearing T cells were detected in the peripheral organs of nude mice 23 wk after grafting with AKR/J thymus and in those of nude mice grafted with AKR/J fetal thymus depleted of macrophages/dendritic cells by incubating with 2'-deoxyguanosine in vitro before grafting. On the other hand, T cells bearing V beta 3, which are selectively related to M1s2a-encoded products of the host phenotype, were expressed neither on the peripheral T cells of nude mice grafted with AKR/J thymus at any stage after grafting nor on those of nude mice grafted with 2'-deoxyguanosine-treated AKR/J thymus. These data suggested that both V beta 6 and V beta 3 T cells were eliminated in the thymus of nude mice grafted with AKR/J thymus, presumably on the basis of interaction with both of graft-derived persisting and host-derived hemopoietic cells in the thymus and that thymic epithelium appears to have little capacity to eliminate T cells reactive to minor lymphocyte stimulating-encoded products.

Functional consequences of a T cell receptor D beta 2 and J beta 2 gene segment deletion

The TCR beta-chain locus of NZW mice carries an 8.8-kb deletion which encompasses the C beta 1, D beta 2, and all six J beta 2 gene segments. On a theoretical basis, the absence of D beta 2 and J beta 2 gene segments in this strain should result in a 70% reduction of the diversity of the TCR repertoire. To experimentally assess the effects of this deletion, we bred the NZW TCR beta-chain allele onto a BALB/c background and tested the ability of this new congenic strain to respond to a panel of 22 random Ag. T cells from BALB/c.beta NZW mice responded to all 22 Ag tested but the magnitude of the response to a large proportion of these Ag (11 of 22) was markedly reduced when compared with T cells from BALB/c mice. Responses to the remaining Ag were either comparable (9 of 22) or occasionally even enhanced (2 of 22) compared with BALB/c mice. In addition, we found that the frequency of V beta 6- and V beta 8.1-bearing T cells was increased by approximately 20% in BALB/c.beta NZW mice. These results suggest that D beta 2 and J beta 2 gene segments are required to maintain a diverse T cell repertoire and that their deletion from the genome may confer a significant selective disadvantage in the wild.

MHC class II A alpha and E alpha molecules determine the clonal deletion of V beta 6+ T cells. Studies with recombinant and transgenic mice

Interactions between MHC class II genes and minor lymphocyte stimulating (Mls) associated products are responsible for clonally deleting self-reactive T cells in mice. Here we demonstrate the role of the intact I-A and I-E molecules as well as the individual A alpha and E alpha chains in the deletion of cells bearing the V beta 6 TCR. DBA/1 (H-2q, Mls-1a) mice were crossed with various inbred congenic, recombinant, and transgenic strains and the F1's were screened for V beta 6 expression. All I-E+ strains were fully permissive in deleting V beta 6+ T cells. I-E- strains expressing I-A b,f,s,k,p permitted only partial deletion, while I-Aq strains showed no deletion. Recombinant I-Aq and I-Af strains which expressed E kappa alpha chain in the absence of E beta chain showed a decrease in V beta 6+ T cells as compared to their H-2q and H-2f counterparts. Furthermore, transgenic mice expressing E kappa alpha Aq beta gene in an H-2q haplotype (E kappa alpha Aq beta?) gave similar results to that of the recombinants in deleting V beta 6 T-cells. The role of the 1-A molecule was also shown by the partial deletion of V beta 6+ T cells in H-2q mice expressing transgenic I-Ak molecules. These results demonstrate that the E alpha chain is important in the deletion of V beta 6 T-cells in Mls-1a mice. The role of A alpha chain is also implied by the permissiveness of E kappa alpha Aq beta but not Aq alpha Aq beta molecules in the deletion of V beta 6+ T cells.

Responses against antigens encoded by the H-3 histocompatibility locus: antigens stimulating class I MHC- and class II MHC-restricted T cells are encoded by separate genes

The purpose of this work was to study the genetic basis of histocompatibility antigens encoded by the mouse minor histocompatibility (H) locus H-3. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted helper T cells (TH) specific for antigens encoded by genes within the H-3 locus were isolated and analyzed. Typing a number of mouse strains for expression of antigens recognized by these TH and CTL suggested that there was a different strain distribution pattern of expression of the antigens recognized by TH compared with those recognized by CTL. Separation of the genes whose products stimulate TH from those whose products stimulate CTL was suggested by: (1) analysis of the strain B10.FS(92NX)/Grf that has undergone recombination within the H-3 region; (2) genetic segregation studies of (B10.UW-H-3b/Sn x C57BL/10Sn)F2 mice; and (3) F1 complementation studies in which CTL specific for products of the TH-defined gene(s) could not be detected, even in the absence of immune responses to products of the CTL-defined genes. Taken together, these data suggest that in addition to two genes (B2m and Cd-1) within the H-3 region whose products typically stimulate class I MHC-restricted CTL, there is at least one additional gene whose product selectively stimulates class II MHC-restricted TH. This new gene is located telomeric from the CTL-defined genes and between the loci we and un on chromosome 2. These data demonstrate a novel degree of complexity of the H-3 "locus" and suggest selective presentation of minor H gene products in the context of class I or class II MHC proteins.

The relative roles of major and minor histocompatibility antigens in the induction of immunologic unresponsiveness by blood transfusion

Renal allograft survival may be prolonged indefinitely in some strains of rats following preoperative transfusion with whole blood from the organ donor. Similarly donor-specific transfusion results in a reduction in the proliferative response of lymph node (LN) white cells (WBCs) to donor-specific stimulators in mixed-lymphocyte culture (MLC). To determine the relative roles of major and minor histocompatibility antigens in the depression of the proliferative response, in vitro lymphocyte proliferation assays were performed using congenic rat strains as blood donors. Unidirectional MLCs were set up between haplotype-disparate responder and stimulator LN cells, in cases in which the responding cells had been harvested from rats transfused with blood that shared either some, all, or none of the major histocompatibility complex genes with the stimulator strain. The proliferative response of LN cells harvested from rats transfused with blood sharing major (class I or II) or minor antigens, or both, with the in vitro stimulator cells was significantly less than the response of cells harvested from nontransfused controls. No single-locus product was more or less effective than whole blood in depressing cell proliferation. These data suggest that the beneficial effect of preoperative random blood transfusions observed in clinical transplantation may arise from the fortuitous sharing by the blood donor and the subsequent organ donor of not only a single major histocompatibility antigen but also of minor histocompatibility antigens.

Selective decreases in T cell receptor V beta expression. Decreased expression of specific V beta families is associated with expression of multiple MHC and non-MHC gene products

Previous reports of TCR V beta usage, studying either expression of a single V beta in a wide panel of strains (6, 7, 10, 12, 13), or expression of multiple V beta s in a very limited strain distribution (14, 15), have identified instances of clonal deletion of potentially autoreactive T cells specific for either self E alpha E beta or minor lymphocyte stimulatory (Mls) antigens. The present study has investigated the range of self antigens that can influence V beta usage by evaluating expression of 16 V beta families in 30 strains of mice. It was found that significant decreases in expression occur in at least 8 of the 16 V beta families and that dominant influences on the T cell V beta repertoire are exerted by expression of Mlsa, Mlsc, and MHC gene products. Decreased expressions of V beta 5, -11, -12, and -16 were influenced by MHC gene products. The patterns of decreased expression seen in intra-MHC recombinant strains and strains of different non-MHC background were distinct for V beta 11, -12, and -16, suggesting that different ligands are involved in the deletion of T cells expressing each of these V beta genes. Mice expressing Mlsa show decreased expression of V beta 9 as well as V beta 6. Mlsc mice lacked V beta 3 expression in those strains where the expressed MHC type was compatible with a strongly stimulatory Mlsc phenotype. V beta 7 was strongly influenced by both MHC and non-MHC products that are not yet identified. These results demonstrate that strain-specific decreases of mRNA expression occur in a major portion of the TCR repertoire. Self antigens including Mlsa, Mlsc, and E alpha E beta, as well as additional MHC and non-MHC products, appear to induce these decreases in expression in the process of eliminating self-reactive T cells from the mature T cell pool.

Analysis of Mlsc genetics. A novel instance of genetic redundancy

The identity of the self determinants involved in the selection of the T cell repertoire has been a matter of considerable interest. In addition to the apparent critical role of MHC gene products, accumulated experimental results indicate the importance of non-MHC gene products in T cell repertoire selection. In particular, murine Mlsa and Mlsc determinants have been shown to be highly stimulatory to allogeneic T cells and to be involved in the negative selection (elimination) of self-reactive T cells expressing selected TCR V beta segments. In this work, a unique phenomenon of genetic redundancy is described in the control of Mlsc expression: Mlsc appears to be controlled by at least two unlinked loci, and the product of either one of these loci is sufficient to evoke Mlsc-specific T cell response and to act as a ligand in the deletion of self Mlsc-reactive V beta 3+ T cells. Based on these findings, we propose a possible explanation for the fact that Mls-like genes or gene products have not been identified in other species such as man.

Preferential restriction of minor alloantigen-specific suppressor T cells to I-E rather than I-A molecules

Suppressor T (Ts) cells specific for minor alloantigens can be generated by intravenous administration of high doses (10(8) cells) of alloantigenic spleen cells. Such Ts cells have previously been shown to inhibit the in vivo induction of CTL responses and are now shown to suppress in vitro proliferative responses to specific minor antigens. This report demonstrates that the activity of such antigen-specific Ts cells in four different strain combinations involving two haplotypes is blocked by anti-I-E antibody. The proliferative helper T cells (Th) in the same strain combinations are restricted to I-A molecules. Whether our results reflect a more general bias of suppressor T cells to be restricted to I-E molecules is discussed.

On the extraordinary capacity of allogeneic epidermal Langerhans cells to prime cytotoxic T cells in vivo

We have examined the relative alloimmunogenicity of monodisperse epidermal Langerhans cells (LC), Thy-1+ dendritic epidermal cells, and keratinocytes prepared from the skins of mice, using appropriate fluorescent-tagged mAb and flow cytometry. Graded doses of each cell type were inoculated i.v. and/or s.c. into allogeneic recipients that were selected on the basis of their degree of immunogenetic disparity with the donors of the epidermal cell (EC) inocula. From 4 to 6 wk later the spleens or draining lymph nodes of recipient mice were assayed for specific priming of cytotoxic T cells. LC proved to be extremely powerful immunogens. As few as 10 MHC-disparate EC primed allospecific T cells of mice that received i.v. or s.c. injected cells. By contrast, at least 10,000 keratinocytes were required to prime appropriate recipients, and then only when these class II MHC-negative cells were injected s.c. Thy-1 dendritic epidermal cells failed to sensitize by any route in the doses employed. With the use of appropriate donor/recipient strain combinations, it was determined that LC can effectively prime cytotoxic T cells specific for diverse types of alloantigens, including determinants encoded by class I and class II MHC genes, as well as minor histocompatibility genes. The results of these in vivo studies confirm that, among EC, the primary alloimmunogenic stimulus resides among LC, and support the hypothesis that LC play a major role in the immunogenicity of skin allografts.

Lymphokine activity production in graft-versus-host reactions across minor histocompatibility antigen barriers

Activated T cells responding to murine minor histocompatibility antigens (HA) were characterized according to the patterns of lymphokine activity production. Although B10.D2/nSN and BALB/c are mutually non-reactive in mixed lymphocyte reaction (MLR), graft-versus-host reaction (GVHR) can be induced by the injection of a large amount of B10.D2/nSN lymphoid cells into irradiated BALB/c recipient mice. Spleen cells from such GVHR mice spontaneously produced interleukin 3 (IL-3)-dependent cell-stimulating activity in cultures, but did not produce interleukin 2 (IL-2). Normal B10.D2/nSN spleen cells also produced IL-3-like activity, but not IL-2 in MLR supernatants, in response to irradiated BALB/c splenocytes. In addition, B-cell stimulatory factor-1 (BSF-1)/interleukin 4 (IL-4) and colony-stimulating factor (CSF) activity were detected in MLR supernatants. The properties of the produced lymphokine activities were similar to those produced in syngeneic transplant mice and syngeneic MLR, but a difference in the time course of lymphokine production existed between GVHR and syngeneic transplant mice. These results indicate that T cells may be activated in vivo in allogeneic transplantation when the donor and the recipient are matched for major HA, and are non-reactive in MLR. Also, the character of lymphokine-producing T cells activated by minor HA may not be qualitatively different from those responding to irradiated syngeneic cells.

Inhibition of MHC class II-restricted T cell response by Lyt-2 alloantigen

T cell hybridomas were established by fusing a CD8+ V beta 8.1+ CTL clone and a CD4+ V beta 8.1+ helper T lymphocyte (HTL) clone to the thymoma cell line BW5147. In contrast to the HTL x BW hybridomas, which retain the same antigen specificity as the original T cell clone, the CTL x BW hybridomas lost the class I MHC-restricted antigen response but acquired a new specificity to Mlsa antigen. Mlsa reactivity of CTL x BW hybridomas was shown to be mediated by the CTL TCR as assayed by inhibition using an anticlonotypic antibody to the CTL clone. Since hybridomas established with BW5147 lose CD8 expression, we have introduced the CD8 molecule into CTL x BW5147 hybridomas by gene transfection. The CD8+ V beta 8.1+ hybridoma was no longer capable of reacting to Mlsa antigen but exhibited the same antigen specificity as the parental CTL clone. Furthermore, the presence of the transfected CD8 molecule in the HTL x BW hybridomas was found to be inhibitory to class II MHC-restricted antigen reactivity. These results demonstrate that, besides its role in increasing the overall avidity of T cell-class I MHC/antigen interaction, the CD8 molecule inhibits T cell-class II MHC gene product/antigen interaction. This negative effect of the CD8 molecule on a class II MHC-restricted response may account for the failure of CD8+ T cells using either V beta 8.1 or V beta 6, which impart reactivity to the Mlsa antigen on CD4+ T cells, to respond to the Mlsa antigen.

Developmental coupling of expression of the Igh-linked minor antigen H-40 to membrane immunoglobulin expression

C.B-20 (Ighb) but not BALB/c (Igha) mice are able to reject BCL1, a spontaneous B cell leukemia of BALB/c origin. The protective immune response is directed toward the minor histocompatibility (H) antigen, H-40, which can be detected by cytotoxic T lymphocytes and is expressed on surface (s) immunoglobulin positive tumor cells including BCL1 as well as sIg+ lymphoblasts activated by lipopolysaccharide. The fact that only sIg+ tumor cells and lymphoblasts express H-40 suggests that sIg itself may be a component involved in CTL recognition of this antigen. However, this possibility was ruled out by demonstrating that removal of sIg from target cells did not prevent H-40-specific CTL recognition. To determine whether H-40 expression was coordinately regulated with that of membrane Ig, we determined whether H-40- sIg- cells acquire H-40 when induced to express sIg. We also transfected a functional mu c and nu region gene into a sIg- lymphoma so that it acquired a sIg+ phenotype. In neither case did such sIg+ cells acquire H-40. Together, these data indicate that H-40 is expressed on B cells representing a particular stage of differentiation that is coincidental with sIg. We previously showed that H-40 and Igh loci are linked on the 12th murine chromosome. In this study we further localized H-40 to a point beyond Aat (formerly Pre-1) near Lm-1, a locus previously described to encode minor H-antigens expressed on lymphomyeloid cells. Thus, H-40 and Lm-1 may represent a gene cluster encoding antigens expressed on subsets of lymphoid and myeloid cells.

Recovery of activated cytotoxic T cells from minor H incompatible tumor graft rejection sites

In this study we determined whether minor H-specific cytotoxic T cells and their precursors (pTc) are present at the site of rejection of minor H disparate tumor allografts. Lymphocytes were retrieved from eyes of BALB/c mice that received subconjunctival injections of minor H-incompatible P815 tumor cells. The lymphocytes were then assayed for direct cytotoxic activity as well as precursor frequency by limiting dilution. Similar assays were conducted on cells obtained from the draining lymph nodes and from the spleen. As expected, tumor rejection was accompanied by significant clonal expansion of minor H-specific pTc within the draining lymph node and the spleen. A correspondingly high frequency of pTc was also detected at the graft site. More importantly, fully functional cytotoxic T cells were recovered from the tumor graft site during rejection, but no similarly active cells were found in either the draining nodes or spleen. We conclude that, after Ag stimulation, pTc are generated in draining central lymphoid compartments. From this generative site, the precursor cells then disseminate systemically, gradually reaching and infiltrating the tumor graft site. A further activation step, dependent upon Ag and T cell help, permits these cells to mature into fully active cytotoxic cells which can then effect tumor rejection. We propose that the terminal stage(s) of pTc activation is promoted by lymphokines released locally from TDH cells that are also generated during the alloimmune response and simultaneously infiltrate the site.

The nature of tolerance in adult recipient mice made tolerant of alloantigens with supralethal irradiation followed by syngeneic bone marrow cell transplantation plus injection of F1 spleen cells

The length of time after syngeneic bone marrow reconstitution when tolerance to alloantigens can be induced in adult mice during T cell differentiation from bone marrow cells was studied by exposing those T cells to (recipient x donor)F1 spleen cells. Supralethally irradiated C3H/He Slc(C3H; H-2k) mice were reconstituted with 1 x 10(7) syngeneic T cell-depleted bone marrow cells and then injected intravenously with 5 x 10(7) (C3H x C57BL/6[B6])F1 (B6C3F1; H-2bxk) or (C3H x AKR/J[AKR])F1 (AKC3F1; H-2kxk) spleen cells at various intervals. In the fully allogeneic combination of B6C3F1----C3H, EL-4 tumor originating from B6 was accepted, and survival of grafted B6 skin was significantly prolonged in the tolerant C3H mice treated with irradiation on day -1 followed by injection of syngeneic bone marrow cells on day 0 plus B6C3F1 spleen cells on days 0, 5, or 10, in a tolerogen-specific manner. In the multiminor histocompatibility antigen-disparate combination of AKC3F1----C3H, AKR skin grafts were permanently accepted in the tolerant C3H mice treated with AKC3F1 spleen cells on days 0, 5, 10, or 15. Immunological parameters, including cytotoxic T lymphocyte activity and delayed foot-pad reaction (DFR), were almost completely suppressed in C3H mice made tolerant of B6 or AKR antigens. A chimeric assay using a direct immunofluorescence method revealed that the tolerant C3H mice given B6C3F1 spleen cells on day 0 were mixed-chimeric for at least 8 weeks after syngeneic bone marrow reconstitution, but not definitely chimeric thereafter. The C3H mice given AKC3F1 spleen cells on day 0 were chimeric even 43 weeks after syngeneic bone marrow reconstitution, but the C3H mice given AKC3F1 spleen cells on day 15 showed temporal chimerism that disappeared within 43 weeks. The untolerant mice were never detectably chimeric. These data suggest that the earlier the timing of the injection of F1 spleen cells after syngeneic bone marrow reconstitution was, the more profound tolerance was induced. Moreover, the stronger the antigenic disparity between donor and recipient, the earlier the injection of F1 spleen cells was required to induce tolerance.

SV40 T antigen acts as a minor histocompatibility antigen of SV40 T antigen tolerant transgenic mice

The ability of normal mice to mount an SV40 T antigen-specific cytolytic T lymphocytes response when immunized in vivo with splenocytes from the SV40 T antigen transgenic 427-line mice and restimulated in vitro with SV40-transformed fibroblasts, or when immunized with SV40 and restimulated with 427-line splenocytes, was analyzed. Both immunization schemes resulted in an SV40 T antigen-specific immune response, indicating the presence of SV40 T antigen-positive cells in the spleens of these transgenic mice. Normal mice engrafted with skin from 427 donors showed no rejection of the graft. Thus, SV40 T antigen in transgenic 427-line mice is expressed on an undefined cell type in the spleen and acts as a tissue-specific minor histocompatibility antigen.

Immune dysfunction associated with graft-versus-host reaction in mice transplanted across minor histocompatibility barriers. I. Depressed antigen-specific antibody responses to bacteriophage phi chi 174

The effect of the graft-versus-host reaction in response to minor histocompatibility antigens on the antibody response to a T-dependent antigen was studied in four strains of mice. Lethally irradiated mice were transplanted with bone marrow plus graded numbers of spleen cells from H-2-compatible donors. Recipients of syngeneic bone marrow transplants and recipients of allogeneic bone marrow depleted of T cells made normal antibody responses to bacteriophage phi chi 174 when immunized on day 28 (primary) and day 56 (secondary) after marrow transplantation. Recipients of allogeneic bone marrow plus spleen cells made only small amounts of specific antibody and failed to make IgG antibody after secondary immunization. The pattern of the depressed antibody response suggests that the primary mechanism of immune dysfunction in mice with the minor antigen GVHR is a lack of T helper cell function.

Prolonged minor allograft survival in intravenously primed mice. Effect of recipient's age and of prior immunity to minor H antigens on the priming cells

The effect of a pretransplant i.v. infusion of donor-strain spleen cells into recipient mice that were already immune to minor H antigens on the infused cells was studied. The central finding is that a preexisting state of immunity against target minor H antigens on a skin graft is sufficient to overcome the survival-prolonging effect of a pretransplant i.v. infusion of donor-strain spleen cells. Moreover, immunity directed against an irrelevant antigen on the infused cells, rather than against a target antigen on the indicator skin graft, is sufficient to cause the beneficial effect of the infusion to be greatly reduced. A further significant finding is that the ability of a pretransplant infusion of donor-strain spleen cells to prolong the survival of a minor allograft of skin declines as the recipient matures from a 6-9-week-old juvenile to a 12-16-week-old adult.