Spontaneous recovery from Friend retrovirus-induced leukemia. Mapping of the Rfv-2 gene in the Q/TL region of mouse MHC.

The Rfv-2 gene that influences the rate of spontaneous recovery from erythroleukemia induced by a low dose of Friend retrovirus complex was mapped to the Q/TL region of mouse MHC. Rfv-2 was physically and functionally distinct from the I-A-linked Ir gene that has been shown to control the responsiveness of Th cells to the envelope glycoprotein of Friend murine leukemia helper virus. The negative effect of the Rfv-2s allele was overcome by the B10.D2-H-2dm1 mutation of the D-L genes of H-2, suggesting functional similarities between the D-L and Q/TL genes in influencing resistance against Friend murine leukemia retrovirus complex infection or possible modification of Q/TL expression by genes in the D-L region.     

Influence of MHC genes on spontaneous recovery from Friend retrovirus-induced leukemia.

Genes influencing the rate of spontaneous recovery from erythroleukemia induced by a low dose of Friend virus complex were located in the right and left portions of the mouse MHC. The right side gene was most likely the previously described Rfv-1 in the H-2D region. Using the B6.C-H-2bm12 mutant mice, the left side gene was mapped to the A beta class II locus. The A beta b was a resistant allele and A beta k and A beta bm12 were susceptible alleles. Genes at this class II locus controlled the responsiveness of Th cells to envelope glycoprotein of Friend murine leukemia helper virus and affected the class switching of virus-neutralizing antibodies from IgM to IgG in FV-infected mice.     

Requirement for CD4+ T Cells in the Friend Murine Retrovirus Neutralizing Antibody Response: Evidence for Functional T Cells in Genetic Low-Recovery Mice

Recovery from infection with the Friend murine leukemia retrovirus complex (FV) requires T-helper cells and cytotoxic T cells as well as neutralizing antibodies. Several host genes, including genes of the major histocompatibility complex (H-2) and an H-2-unlinked gene, Rfv-3, influence these FV-specific immune responses. (B10.A × A/Wy)F₁ mice, which have the H-2^a/a Rfv-3^r/s genotype, fail to mount a detectable FV-specific T-cell proliferative response but nevertheless produce FV-specific neutralizing immunoglobulin M (IgM) antibodies and can eliminate FV viremia. Thus, this IgM response, primarily influenced by the Rfv-3 gene, may be T-cell independent. To test this idea, mice were depleted of either CD4⁺ or CD8⁺ T-cell populations in vivo and were monitored for the effect on the neutralizing antibody response following FV infection. Surprisingly, mice in which CD4⁺ cells were depleted showed undetectable FV-neutralizing antibody responses and high viremia levels compared to nondepleted or CD8-depleted animals. In addition to knocking out the FV antibody response, CD4⁺ T-cell depletion reduced survival time significantly, further indicating the importance of CD4⁺ T cells. These studies revealed the first evidence for a functional T-cell response following FV infection in these low-recovery mice and showed that CD4⁺ T-helper cells are required for the Rfv-3-controlled FV antibody response.     

Major histocompatibility complex class I gene controls the generation of gamma interferon-producing CD4(+) and CD8(+) T cells important for recovery from friend retrovirus-induced leukemia

Recovery from leukemia induced by Friend virus complex (FV) requires strong CD4(+) helper, CD8(+) cytotoxic T-lymphocyte, and B-cell responses. The development of these immune responses is dependent on the major histocompatibility complex (MHC) (H-2) genotype of the mouse. In H-2(b/b) mice, which spontaneously recover from FV-induced erythroleukemia, neutralization of gamma interferon (IFN-gamma) in vivo inhibited recovery, which indicated that IFN-gamma was a necessary component of the immune response to FV. Furthermore, in H-2(b/b) mice, high numbers of IFN-gamma-producing cells were detected after FV infection, whereas in H-2(a/b) mice, which have a low-recovery phenotype, only low numbers of IFN-gamma-producing cells were detected. Similarly, H-2(bm14/b) mice, which cannot recover from FV infection due to a point mutation in one allele of the H-2D(b) gene, also had low numbers of IFN-gamma-producing T cells. Surprisingly, this effect was observed for both CD8(+) and CD4(+) T cells. These findings reveal a novel influence of MHC class I genes on CD4(+) T-cell responses to viral infection. Furthermore, the influence of MHC class I genotype on the generation of both IFN-gamma-producing CD4(+) and CD8(+) T cells helps explain the major impact of the H-2D gene on recovery from FV disease.     

Expression of hemopoietic histocompatibility antigens on H-2-loss variants of F1 hybrid lymphoma cells: evidence consistent with trans gene regulation

H-2 heterozygous marrow stem cells, lymphoid progenitor cells, and leukemia/lymphoma cells do not express hemopoietic or hybrid histocompatibility (Hh) antigens, which are important transplantation antigens recognized during the rejection of normal or neoplastic hemopoietic cells. The Hh-1b determinant of the H-2b haplotype maps to the D region of H-2. We have tested the hypothesis that gene(s) at or near H-2D of the H-2d haplotype down-regulate the expression of Hh-1b in the trans configuration. We used Abelson leukemia virus-transformed pre-B lymphoma cells (ACCb) of BALB/c X BALB.B (H-2d X H-2b) origin, as well as variant lines of ACCb, which were selected for resistance to monoclonal anti-H-2 antibodies plus complement. B6D2F1 (H-2b X H-2d), C3B6F1 (H-2k X H-2b), or B6 (H-2b) mice were infused with inocula of 5 X 10(6) B6 bone marrow cells (BMC). Proliferation of donor-derived marrow cells was judged in terms of DNA synthesis by measuring the splenic incorporation of 5-iodo(125I)-2'-deoxyuridine (IUdR) 5 days after cell transfer. B6 BMC grew much better in B6 than in F1 hybrid host mice, an expression of "hybrid resistance". As observed previously, the injection of EL-4 (H-2b, Hh-1b) tumor cells prior to infusion of B6 (H-2b, Hh-1b) BMC enhanced the growth of B6 BMC in F1 hybrid mice. Therefore, this in vivo "cold target cell competition" type of assay can be used to detect the expression of Hh-1b antigens. Unlike EL-4 (H-2b) cells, hybrid resistance was not affected by prior infusion of (H-2b X H-2d) heterozygous ACCb cells. In contrast, three ACCb variant cell lines, H-2d-, Ld-Dd-, and Dd-, enhanced the growth of B6 BMC in F1 hosts. The ACCb H-2b- cell line did not affect hybrid resistance to B6 BMC. The loss of gene expression on the H-2d chromosome at or very near the H-2Dd locus is correlated with the appearance Hh-1b, as determined by the in vivo cold target competition assay. These results support the hypothesis that heterozygous cells possess trans-acting, dominant, down-regulatory genes mapping near H-2D that control the Hh-1 phenotype of lymphoid tumor cells.     

H-2D(b-/-) mice are susceptible to persistent infection by Theiler's virus

H-2(b) mice are resistant to persistent infection of the central nervous system by Theiler's virus. They clear the infection 7 to 10 days after intracranial inoculation. Resistance maps to the H-2D gene and not to the H-2K gene and is associated with a potent antiviral cytotoxic T-lymphocyte (CTL) response. We used H-2(b) mice in which the H-2D or the H-2K gene had been inactivated to dissect the respective roles of these genes in resistance. We report that H-2D(-/-) but not H-2K(-/-) mice were susceptible to persistent infection. Furthermore, whereas H-2K(-/-) mice mounted a vigorous virus-specific CTL response, similar to that of control C57BL/6 mice, the CTL response of H-2D(-/-) mice was nil or minimal. Using target cells transfected with the H-2D(b) or the H-2K(b) gene, we showed that the H-2K-restricted CTL response against the virus was minimal in H-2D(-/-) mice. These results demonstrate that the H-2D(b) and H-2K(b) genes play nonredundant roles in the resistance to this persistent infection.     

Induction of anti-AKR/gross virus cytolytic T lymphocytes in AKR.H-2b:Fv-1b congenic mice: age-dependent conversion to a nonresponder phenotype

Previously, we reported that the generation of cytolytic T lymphocytes (CTL) specific for syngeneic tumors induced by AKR/Gross leukemia viruses was under multi-gene control. Thus, although carrying the required immune response gene(s) encoded by the H-2b haplotype and characteristic of responder strains such as C57BL/6, AKR.H-2b congenic mice failed to mount antiviral CTL responses. Young adult AKR.H-2b:Fv-1b "doubly congenic" mice, however, were able to generate specific anti-AKR/Gross virus CTL activity. These results demonstrated that the positive effect of MHC-encoded immune response gene control could be overcome by the action of the Fv-1n allele. The responder status of the B6.Fv-1n congenic, however, indicated that this Fv-1n-mediated inhibition was dependent on the interaction of Fv-1n with another gene(s) encoded by the AKR background. The results of experiments performed with AKXL recombinant inbred mice further suggested that a single additional genetic locus, encoding the Akv-1 provirus, was necessary along with Fv-1n to cause inhibition of antiviral CTL generation. Here we show that the responsiveness of AKR.H-2b:Fv-1b mice is dependent on their age. Thus, with moderate aging these doubly congenic mice converted to a nonresponder status with respect to anti-AKR/Gross virus CTL production: 85% of mice less than or equal to 9 wk of age responded compared with 0% of mice greater than 9 wk old. As with nonresponder AKR.H-2b mice, an inverse correlation was observed between CTL responsiveness and the expression of CTL-defined viral antigens by normal cells. Namely, spleen cells from young AKR.H-2b:Fv-1b mice showed little or no expression of such viral antigens, whereas with moderate aging there was a steady increase in their display. These results are discussed with reference to possible mechanisms of unresponsiveness of AKR.H-2b vs moderately aged AKR.H-2b:Fv-1b mice, and with respect to the utility of this system as a model for naturally occurring retrovirus infections and the interactions of retroviruses with the immune system.     

AKR/J gene(s) unlinked to H-2 determines dominant inheritance of lymphocyte hyporesponsiveness to acetylcholine receptor

Mice with the H-2b major histocompatibility complex haplotype are high immune responders to nicotinic acetylcholine receptors (AChR), whereas mice with the H-2k haplotype are generally low responders. F1 progeny of C57BL/6 (H-2b) mice crossed with mice of most H-2k strains are high responders to AChR in standard conditions of testing helper T cell proliferation in vitro (4 X 10(5) lymph node cells/microwell, 1 wk after primary challenge in vivo). In contrast, the F1 progeny of AKR/J (H-2k) crossed with high responder (H-2b) strains (B6, A.BY, or C3H.SW) were all hyporesponsive to AChR when lymphocytes were tested at 4 X 10(5) cells/well. However, at a density of 1 X 10(6) or greater/well, a high level of antigen-specific responsiveness was demonstrable in the F1 hybrid lymphocytes. A shift from low to high responsiveness to AChR at high cell densities was observed also in the H-2b strain AKR.B6. Other strains previously demonstrated to be low responders to AChR did not become responsive to AChR when lymphocyte numbers were increased to 1.4 X 10(6)/well. The N2 generation yielded by backcrossing (AKR X B6)F1 mice to AKR/J were all low responders, whereas N2 progeny derived by backcrossing F1 to B6 were high or low responders in a ratio of approximately 1:1 (independent of their H-2 phenotype). Results consistent with this observation were obtained in (AKR X B6) F2 mice. These data suggest that at least one AKR/J gene outside of the H-2 complex exerts a hyporesponsive influence on the I-A-dependent helper T cell response to AChR in H-2b mice.     

Ir gene control of the cytotoxic T lymphocyte response to Sendai virus: H-2k mice are low responders to Sendai

H-2k mice generate a secondary in vitro cytotoxic T lymphocyte response to Sendai virus 20- to 100-fold weaker than those of other haplotypes tested (H-2b,d,q,s). This immune response defect maps to both H-2K and H-2D. H-2k x H-2d F1 mice (responder x nonresponder) only lyse targets that have the d allele at H-2K and/or H-2D. H-2k targets are equally lysable with anti-Sendai antibody. Furthermore, H-2k mice demonstrate normal antibody and T cell proliferation responses to Sendai virus. The Ir gene defect therefore appears to be limited to the generation of the cytotoxic T lymphocytes.     

Regulation of idiotope expression. III. H-2 influences the magnitude and the idiotypy of a T-independent antibody response in mice of certain genetic backgrounds

Antibody response to the phosphocholine (PC) epitope on Streptococcus pneumoniae R36a (Pn), a T-independent Ag type 2, was studied in H-2 congenic mouse strains. The PC-specific antibody plaque-forming cells (PFC) were enumerated in the spleen at various intervals after the primary Pn injection, and the proportion of PFC that produced antibody expressing the AB1-2 idiotope (Id) was determined by using the corresponding monoclonal anti-Id. AB1-2 is a cross-reactive Id, detectable on germline-encoded PC antibody of the T15 family, and on most, but not all, somatic variants of that antibody. The specific PFC responses in BALB/c (H-2d) and BALB.B (H-2b) strains were of comparable magnitude and most, if not all, PFC were ABl-1 Id-positive (AB1-2+). This was not the case in the responses of the B10D2 (H-2d) vs C57BL/10 (H-2b) strains and the D1.C (H-2d) vs D1.LP (H-2b) strains (on DBA/1 background). In each of these pairs, the H-2d mice were high responders, and the response was dominated by AB1-2 Id (greater than or equal to 80% AB1-2+ PFC at the peak, on day 5). The H-2b mice were low responders, and only a minor proportion of PFC (less than or equal to 30%) were AB1-2+; an increase of AB1-2+ was seen later in the response (d.10). The results of PFC assays were confirmed by measuring the PC-binding antibody and AB1-2 Id in the sera of D1.C and D1.LP mice immunized repeatedly with Pn. Moreover, D1.LP mice that had very low levels of AB1-2 Id had higher serum levels of antibody expressing two other T15 Id, B36-82, and B24-44. The B36-82 and B24-44 Id have been previously found on somatic variants of PC antibody expressed independently of the Ab1-2 Id. The concentrations of these two Id in D1.LP mice after repeated immunization approached those in D1.C. These results indicate that 1) the H-2 allelism may have a significant effect on TID antibody response in mice of a certain genetic background, but not in the BALB/c; and 2) the idiotypic repertoire of the response may be influenced by H-2 at the level of clonal variants of PC-reactive cells.     

Recombinants in the H-2S/H-2D interval of mouse chromosome 17 define the map position of a gene for cleft palate susceptibility

The H-2 region of mouse chromosome 17 is known to include one or more genes that affect susceptibility to cortisone-induced cleft palate. We have now studied congenic strains that possess crossovers in the interval between H-2S and H-2D and have observed significant differences in susceptibility among recombinants that had been believed to possess the same H-2 haplotypes. Pregnant mice were injected on days 11 through 14 of gestation with 100 mg of cortisone per kg of body weight. The frequency of cleft palate in B10.A(2R) was significantly greater than in B10.A(1R), despite the fact that both have H-2a/H-2b crossovers in the interval between the S and D loci and have the same alleles at all loci that have been previously characterized. Both B10.BAR5 and B10.BAR12 were significantly more susceptible than B10.A(18R), although these strains also share the same alleles at all loci that have been previously characterized. All three of these strains have H-2b/H-2a recombinant chromosomes, with crossovers in the S/D interval. Genetic linkage between H-2 and the high-susceptibility gene of B10.BAR5 was confirmed by testing H-2 homozygotes derived by intercrossing backcross animals. These data therefore suggest that a gene coding for susceptibility, which we designate Cps-1, maps in the 350-kb interval between H-2S and H-2D, and the congenic strains that we have found to be different have different crossover points within this interval. Alleles at the Cps-1 locus have embryonic effects, but no demonstrable effects on the maternal environment.     

H-2-associated and background genes influence the development of a murine retrovirus-induced immunodeficiency syndrome

Host genetic determinants of resistance or susceptibility to a retrovirus-induced immunodeficiency syndrome, termed MAIDS, were evaluated in Fv-1b mice infected with the mixture of ecotropic, MCF, and defective murine leukemia viruses designated LP-BM5 murine leukemia viruses. Genes of the MHC were shown to exert a major influence on the development of disease and the extent of virus spread in mice infected as adults. Strains bearing the b, f, k, q, r, and s haplotypes were moderately to highly susceptible to MAIDS whereas mice of the d haplotype were the most resistant. Resistance to disease was strongly associated with inhibition of mink cell focus-inducing virus spread and, to a lesser extent, with inhibition of ecotropic virus expression. Mapping studies localizing resistance associated with the d haplotype to H-2Dd were confirmed by the demonstration that B6 mice carrying this gene as a transgene or by recombination were resistant to disease. Penetrance of resistance to disease associated with expression of H-2Dd was markedly influenced by MHC genes mapping to the left of H-2D and by non-MHC loci such that some strains bearing this gene were highly susceptible to MAIDS. The combined effects of MHC and background genes among 40 strains examined yielded a remarkably wide spectrum of disease phenotypes with the onset of advanced disease ranging from 10 wk to 72 wk postinfection. Resistance to disease in moderately to highly resistant strains was shown to develop with age. Unexpectedly, the disease resistant phenotype was found to be a recessive trait.     

Genes of the H-2 complex regulate the antibody response to murine leukemia virus

The influence of the major histocompatibility complex of the mouse (H-2 complex) on the antibody response against murine leukemia virus (MuLV) was investigated after 3 different ways of virus presentation (milk transmission of virus, spontaneous virus activation, and immunization with inactivated virus). The antibody response against MuLV was measured in the sera of H-2 congenic C57BL V+ sublines (V+ denotes positive for milk-transmitted MuLV), (B10.AV+ X C57BL)F1 mice, (C57BL X AKR)F1 mice and of C57BL animals after immunization with inactivated AKR virus. The pattern of immune responsiveness of the different C57BL strains to MuLV was independent of virus replication and was similar for the 3 ways of virus presentation. Serum antibody levels were controlled by 2 genes within the H-2 complex. The first gene (Ir-MuLV-1) was located in the I-A region and was complemented by a second gene (Ir-MuLV-2), which was situated in the regions to the right of the I-B region. Presence of 2 responder alleles (Ir-MuLV-1+,2+) led to an optimal antibody response (H-2b haplotype). Animals that only expressed a responder allele in the I-A region (Ir-MuLV-1+,2-) were intermediate responders. Animals lacking a responder allele in the I-A region (Ir-MuLV-1-,2+ or Ir-MuLV-1-,2-) were low responders.     

Expression of CTL-defined, AKR/Gross retrovirus-associated tumor antigens by normal spleen cells: control by Fv-1, H-2, and proviral genes and effect on antiviral CTL generation

In previous studies we have characterized H-2-restricted cytolytic T lymphocytes (CTL) type specific for Gross cell surface antigen-positive tumor cells induced by AKR/Gross leukemia viruses. The generation of such CTL was shown to be controlled by at least three genetic loci including H-2 and Fv-1. The Fv-1n phenotype was able to negate positive immune response gene effects of the H-2b haplotype. Fv-1n-mediated inhibition appeared to operated by allowing the early expression by normal cells of N-ecotropic leukemia virus-related antigens recognized by the antiviral CTL, perhaps via tolerance induction. In the present study, the expression of CTL-defined viral antigens by normal cells is further considered. Possible gene dosage effects by H-2 as well as Fv-1 and the other virus-related (V) genes, including proviral structural loci, were examined by comparison of a panel of congenic and F1 mice. These experiments indicated that the quantitative level of expression of CTL-defined viral antigens was primarily controlled by the Fv-1 genotype. Gene dosage effects were also observed for the V genes and, in some situations, for H-2. The importance of the early display of viral antigens by normal cells was underscored by the inability of those mice to generate specific antiviral CTL responses. Even strains expressing low levels of viral antigens, such as responder X nonresponder (AKR.H-2b:Fv-1b X AKR.H-2b)F1 mice, failed to respond. These results are discussed with respect to the inability of mice of the AKR background to respond with specific antiviral CTL generation and in light of their high incidence of spontaneous leukemia.     

Genetic control of the induction of cytolytic T lymphocyte responses to AKR/Gross viral leukemias. II. Negative control by the Fv-1 locus in AKR mice of responder H-2b haplotype

To assess whether the presence of a responder H-2b haplotype would be sufficient to allow mice of nonresponder "high leukemic" phenotype to generate syngeneic anti-AKR/Gross virus cytolytic T lymphocytes (CTL), the AKR.H-2b strain was examined. Although capable of mounting vigorous apparent anti-minor histocompatibility-specific CTL responses, AKR.H-2b mice failed to produce anti-viral CTL after a variety of stimulation protocols. In contrast, the "doubly congenic" AKR.H-2b:Fv-1b strain was able to respond with substantial levels of H-2-restricted anti-AKR/Gross virus CTL activity. These results indicated that Fv-1n alleles could exert negative epistatic control over responder H-2b-encoded gene(s). Because the B6.Fv-1n congenic was also able to generate anti-viral CTL indistinguishable from the prototype B6 strain, however, it was apparent that other genes of AKR background were required for the Fv-1n-mediated inhibition in AKR.H-2b mice. The mechanism by which Fv-1 intereacted with other genes to override positive H-2b control appeared to be related to the expression of the CTL-defined, virus-associated antigens by normal AKR.H-2b cells. Thus, AKR.H-2b spleen cells but not thymus cells were able to stimulate the production of B6 anti-AKR/Gross virus CTL and were recognized as target cells by such anti-viral CTL. In contrast, both spleen cells and thymocytes from AKR.H-2b:Fv-1b mice were negative when tested as stimulator or target cells in these assays. In addition, AKR.H-2b but not AKR.H-2b:Fv-1b spleen cells were shown to display serologically defined gp70 determinants and the Gross cell surface antigen. Taking these data together, it appeared that the inhibition of anti-viral CTL responsiveness might be due to tolerance induced by the cell surface expression of virus-associated antigens by normal AKR.H-2b cells. Widespread display of viral antigens, in turn, may have been due to the permissive effects of Fv-1n on the spread of the early arising N-ecotropic, endogenous AKR leukemia virus controlled by other background genes. In this context, the implications of the multi-gene control of anti-AKR/Gross virus CTL production are discussed with respect to the induction of spontaneous leukemia in the high incidence AKR strain.     

Genetic control of sensitivity to Moloney leukemia virus in mice. II. Mapping of three resistant genes within the H-2 complex.

The level of viremia and the appearance of leukemias were studied after inoculation wtih Moloney leukemia virus (M-MuLV) in different H-2 congenic strains of mice. The viremia was regularly measured on individual mice with a radioimmunoassay of the major internal virion component p30. Three genes within the major histocompatibility complex controlled the level of circulating virus. Two of them, called Rmv.1 and Rmv.2, appear to be located in the I region, respectively, in the IA, and the IC-S or G regions. The third gene, Rmv.3, was mapped to the D end of the complex in the D or T region. Crosses between resistant and sensitive strans demonstrated that the H-2 associated resistance was inherited as a dominant or semi-dominant Mendelian trait. Rmv.1, Rmv.2, and Rmv.3 were shown to complement for resistance in trans when the hybrids between sensitive strains were examined. A good correlation was found between viremia and the appearance of leukemias, the most viremic strains being also the most leukemic. Nevertheless, additional non-H-2 genes must control viremia and/or the appearance of leukemia since, despite high levels of viremia, some sensitive strains do not become leukemic.     

Dissociation of H-2 recognition by antibody and cytotoxic T cells of a cloned murine leukemia cell line

The differential expression of H-2 specificities recognized by antibody and by cytotoxic T lymphocytes (CTL) has been studied using a clone (FY7) of the C57BL/6 leukemia cell line FBL-3 (H-2b/H-2b). Unlike C57BL/10 spleen cells, EL-4 lymphoma cells and Y57-2C leukemia cells (all H-2b/H-2b), FY7 failed to induce the primary in vitro generation of anti-H-2b CTL by (B10.A x A)F1 (H-2a/H-2a) or B10.D2 x BALB/c)F1 (H-2d/H-2d) responder spleen cells. In addition, FY7 was not lysed by, and did not competitively inhibit anti-H-2b CTL. Quantitative absorption tests with H-2Kb and H-2Db antisera revealed that FY7 expressed these antigens in quantitatively similar amounts to EL-4. The H-2Kb product of FY7 appeared to be identical with that of C57BL/10 spleen cells both in apparent molecular weight and isoelectric point. Yet FY7 failed to inhibit anti-H-2Kb CTL competitively in a cold target inhibition assay. Possible mechanisms are discussed for the lack of T-lymphocyte recognition of the H-2Kb-gene product expressed by FY7.     

Hierarchal Utilization of Different T-Cell Receptor Vβ Gene Segments in the CD8+-T-Cell Response to an Immunodominant Moloney Leukemia Virus-Encoded Epitope In Vivo

The CD8(+)-T-cell response to Moloney murine leukemia virus (M-MuLV)-associated antigens in C57BL/6 mice is directed against an immunodominant gag-encoded epitope (CCLCLTVFL) presented in the context of H-2D(b) and is restricted primarily to cytotoxic T lymphocytes (CTL) expressing the Valpha3.2 and Vbeta5.2 gene segments. We decided to examine the M-MuLV response in congenic C57BL/6 Vbeta(a) mice which are unable to express the dominant Valpha3.2(+) Vbeta5.2(+) T-cell receptor (TCR) due to a large deletion at the TCR locus that includes the Vbeta5.2 gene segment. Interestingly, M-MuLV-immune C57BL/6 Vbeta(a) mice were still able to reject M-MuLV-infected tumor cells and direct ex vivo analysis of peripheral blood lymphocytes from these immune mice revealed a dramatic increase in CD8(+) cells utilizing the same Valpha3.2 gene segment in association with two different Vbeta segments (Vbeta3 and Vbeta17). Surprisingly, all these CTL recognized the same immunodominant M-MuLV gag epitope. Analysis of the TCR repertoire of individual M-MuLV-immune (C57BL/6 x C57BL/6 Vbeta(a))F(1) mice revealed a clear hierarchy in Vbeta utilization, with a preferential usage of the Vbeta17 gene segment, whereas Vbeta3 and especially Vbeta5.2 were used to much lesser extents. Sequencing of TCRalpha- and -beta-chain junctional regions of CTL clones specific for the M-MuLV gag epitope revealed a diverse repertoire of TCRbeta chains in Vbeta(a) mice and a highly restricted TCRbeta-chain repertoire in Vbeta(b) mice, whereas TCRalpha-chain sequences were highly conserved in both cases. Collectively, our data indicate that the H-2D(b)-restricted M-MuLV gag epitope can be recognized in a hierarchal fashion by different Vbeta domains and that the degree of beta-chain diversity varies according to Vbeta utilization.     

Cell-mediated cytotoxicity against allogeneic mutant H-2 antigens: restricted and nonrestricted responses

Two "gain and loss" type mutations of the H-2D region, the H- 2bm13 and H- 2bm14 , resulted in the expression of noncross-reactive CML determinants that are unique to each mutation, the Dbm13 gains and Dbm14 gains, respectively. According to the results of direct cytolytic and competitive inhibition assays of in vitro induced primary cytotoxic T lymphocytes, allogeneic responses specific for Dbm13 gains are generated by responders bearing the H-2b ( KbIbDb ) haplotype, but not by responders bearing the H- 2bm14 ( KbIbDbm14 ), KbIbDd , KbIbDk , or KbIb / qDq haplotype. Responses by the non-H-2b responders against Dbm13 are limited to those determinants shared by the Dbm13 and Db molecules. Because congenic mice differing only at the H-2D region are either responsive or nonresponsive to Dbm13 gains, the responsiveness is controlled by gene(s) in the H-2D region. F1 hybrid offspring of responsive (H-2b) and nonresponsive (non-H-2b) parents are invariably responsive, indicating genetic dominance of the responsiveness. In contrast to the response against Dbm13 gains, cytotoxicity specific for Dbm14 gains is generated by responders bearing the H-2b, H- 2bm13 , KbIbDd , KbIbDk , or KbIb / qDq haplotype. These data indicate the existence of two types of allogeneic MHC determinants; one, represented by Dbm14 gains, is the classic type capable of eliciting CML responses in mice of a wide range of H-2 haplotypes, whereas the other, exemplified by Dbm13 gains, elicits CTL responses only in mice of a few related haplotypes. It is proposed that recognition of Dbm13 gains is restricted by structures shared by Db and Dbm13 but missing from other D (or L, R, etc.) molecules, such as Dbm14 , Dd, Dk, and Dq. Availability of various restricting structures in self MHC molecules may thus influence the alloreactive CTL repertoire.     

Genetic control of the humoral response to an H-2 public specificity.

The humoral response of mice to an H-2 public specificity, termed H-2. '28' was found to be under genetic control. The genes determining this specificity were mapped to both the H-2K and H-2D regions, suggesting possible structural homologies between the products determined by these two regions. Genetic analyses indicated that a single non-H-2-linked gene regulates the anti-H-2. '28' response. In a backcross study, no linkage was detected between this putative H-2. '28' Ir gene and either the V H region or the Ly-2 locus to which the K-light chain locus is linked. Thus, a regulatory rather than a structural genetic locus seems a more likely basis for differences in response to this antigen. Our data further indicate that control of the humoral response to H-2. '28' is determinant specific since responses of the same backcross mice to other K and D alloantigens were not found to be subject to the same control.