Genetic analysis of the non-H-2-linked Ir genes controlling the cytotoxic T-cell response to H-Y in H-2d mice

Concomitant tumor and minor histocompatibility antigen-specific immunity initiate rejection and maintain remission from established spontaneous solid tumors

Nonmyeloablative hematopoietic cell transplantation can cure patients with hematologic malignancies but has reported limited success against solid tumors. This is possibly because of profound peripheral tolerance mechanisms and/or suboptimal tumor recognition by effector T lymphocytes. We report that in mice developing spontaneous prostate cancer, nonmyeloablative minor histocompatibility mismatched hematopoietic stem cell transplantation, and donor lymphocyte infusion of unmanipulated lymphocytes combined with posttransplant tumor-specific vaccination circumvents tumor-specific tolerance, allowing acute tumor rejection and the establishment of protective immunosurveillance. Although donor-derived tumor-specific T cells readily differentiated into effector cells and infiltrated the tumor soon after infusion, they were alone insufficient for tumor eradication, which instead required the concomitance of minor histocompatibiltiy antigen-specific CD8(+) T-cell responses. The establishment of protective immunosurveillance was best induced by posttransplant tumor-specific vaccination. Hence, these results provide the proof of principle that tumor-specific T-cell responses have to be harnessed together with minor histocompatibility responses and sustained by posttransplant tumor-specific vaccination to improve the efficacy of allotransplantion for the cure of solid tumors.

Antisense targeting of cFLIP sensitizes activated T cells to undergo apoptosis and desensitizes responses to contact dermatitis

Contact dermatitis is the result of inflammatory responses mediated by hapten-specific activated CD8+ and CD4+ T cells. Activation-induced cell death (AICD) is a naturally occurring process regulating the resolution of T-cell responses through decreased expression of the antiapoptotic molecule cellular FLICE inhibitory protein (cFLIP). We show that targeting cFLIP expression in vitro and in vivo, with morpholino antisense applied systemically or topically in conjunction with antigen, sensitizes T cells to undergo "early" AICD resulting in tolerance. Analysis of antisense-treated CD8+ OT-1 splenocytes after co-culture with SIINFEKL-pulsed DCs showed apoptosis occurring in a dose-dependent manner with respect to cFLIP peptide-conjugated phosphorodiamidate morpholino oligomer (PPMO) concentration. A transplant acceptance model using male DO.11 donor cells and female BALB/c recipient mice showed that cFLIP antisense treatment could promote antigen tolerance. Hypersensitivity responses induced in mice by the epicutaneous application of the haptens FITC and oxazolone confirmed that topically applied cFLIP antisense could reduce inflammation. Treatment of the skin produced significant reduction in dermatitis and localized infiltration of lymphocytes. Moreover, the treatment was target- and antigen-specific, dose-dependent, and capable of inducing long-lived tolerance. These data suggest that the targeted expression of immune-regulating molecules is possible through the application of antisense to the skin.

Fate of orthotopic corneal allografts in C57BL/6 mice

Our aim was to determine whether corneal allografts placed in normal eyes of C57BL/6 mice enjoy immune privilege, and whether recipients of long-standing grafts acquire donor-specific ACAID. C57BL/6 mice received corneal grafts from BALB/c, C57BL/6, C3H, B10.D2 or BALB.B mice; for comparison, BALB/c mice received C3H or C57BL/6 corneal allografts. Delayed hypersensitivity and anterior chamber associated immune deviation (ACAID) induction were assessed in recipient mice at four and eight weeks after grafting. It was found that C57BL/6 mice resemble BALB/c mice in mounting more vigorous rejection reactions against minor H, rather than MHC, alloantigenic corneas, and in the acquisition of donor-specific DH within four weeks of engraftment. In addition, C57BL/6 mice with long-standing, healthy allografts display donor-specific ACAID. However, C57BL/6 mice differ from BALB/c mice in that (1) fewer allodisparate corneal grafts were accepted indefinitely; and (2) rejection in these eyes correlated with sustained donor-specific DH. It was concluded that immune privilege is less secure in the eyes of C57BL/6 mice, compared to BALB/c mice. This conclusion is discussed in terms of known polymorphic differences between these mouse strains at genetic loci governing (a) immune responsiveness, (b) alloform of Fas ligand, and (c) bias of immune response toward Th1 or Th2 phenotypes.

The male-specific histocompatibility antigen, H-Y: a history of transplantation, immune response genes, sex determination and expression cloning

H-Y was originally discovered as a transplantation antigen. In vivo primary skin graft responses to H-Y are controlled by immune response (Ir) genes mapping to the MHC. In vitro T cell responses to H-Y are controlled by MHC class I and II Ir genes, which-respectively, restrict CD8 and CD4 T cells: These can be isolated as T cell clones in vitro. T cell receptor (TCR) transgenic mice have been made from the rearranged TCR genes of several of these, of which that specific for H-Y/Db is the best studied. Non-MHC Ir genes also contribute to the control of in vitro CTL responses to H-Y. The Hya/HYA gene(s) encoding H-Y antigen have been mapped using translocations, mutations, and deletions to Yq in humans and to the short arm of the Y chromosome in mice, where they lie in the deletion defined by the Sxrb mutation between Zfy-1 and Zfy-2. Hya/HYA has been separated from the testis-determining gene, Sry/SRY, in both humans and mice and in humans the azoospermia factor AZF has been separated from HYA. In mice transfection of cosmids and cDNAs mapping to the Sxrb deletion has identified two genes encoding H-Y peptide epitopes. Two such epitopes, H-Y/K(k) and H-Y/D(k), are encoded within different exons of Smcy and a third, H-Y/D(b), by a novel gene, Uty. Peptide elution approaches have isolated a human H-Y epitope, H-Y/HLA-B7, and identified it as a product of SMCY. Each of the Hya genes in mice is ubiquitously expressed but of unknown function. Their X chromosome homologues do not undergo X inactivation.

Regulation by non-major histocompatibility complex genes of the allo-4-hydroxy-phenylpyruvate dioxygenase (F liver protein) response

Although rapid progress is being made in the quantitative genetics of multifactorial disease, no response to a simple antigen has yet been subjected to full genomic analysis. The well-characterized antigen allo-HPPD (4-hydroxy-phenylpyruvate dioxygenase, previously known as F liver antigen) is a good candidate for such treatment. Old and new data bearing on this possibility are here assembled. In respect of antibody production and an early burst of interleukin-4 (IL-4) transcription, introduction of the non-major histocompatibility complex (MHC) background from A/J strain mice into F1 hybrids with C57BL10 strains up-regulates the response. These findings can be aligned with previous quantitative genetics carried out on airway hyper-responsiveness in related strains, and to a lesser extent with the genetics of autoimmune diabetes in the mouse. Taken together, the findings suggest that regulation of the pro-inflammatory cytokines are largely responsible for the variation. Additional data indicate that these non-MHC genes are are to a variable extent (depending on the response parameter) epistatic to the down-regulatory MHC allele H-2Ab.

Continued mapping of chromosome 2 genes

This report describes our continued efforts to elucidate the genetic fine structure of the central portion of the mouse chromosome (Chr) 2. Mice from our panel of 28 Chr 2 congenic strains were tested: 1) for the presence of the antigens which stimulate Chr 2-reactive lymphocyte clones in mixed lymphocyte reaction (MLR); 2) for the antigens of histocompatibility (H) genes H-42a and H-45a as determined by allograft rejection; and 3) for their ability to respond to the H-Y antigen in a cell-mediated lysis assay. The results obtained in this study have allowed additional mapping of immunologically involved Chr 2 genes. The gene encoding the antigen which stimulates lymphocyte clone 1C11 can be considered wholly different from other Chr2 H genes on the basis of chromosomal recombination. We have assigned the symbol H-48 to this gene. The following gene order has been established: [H-3, B2m, pa], we, [H-42, H-48,] H-45, IR-H-Y, Hd-1, un, H-13, Aw. The order of the bracketed genes is not known. H-44 maps centromeric to IR-H-Y. The genes encoding the antigens that stimulate lymphocyte clones 2G7, 2C10, 1F6, 1B10, and 1H10 map centromeric to H-45.

Additional mapping of mouse chromosome 2 genes

The purpose of this work was to elucidate the genetic fine structure of the central portion of mouse chromosome (Chr) 2. Seven Chr 2 congenic mouse strains [B10.PA(L)-pa we un at, B10.PA(L)-pa Aw, B10.PA(L)-we un at, B10.PA(J)-pa a, B10.FS-we Aw, B10.C-we Aw, and B10.YBR-a] were produced. Breeding studies were carried out using strains B10.PA(L)-pa we un at and B10.LP-H-13b to accurately determine the recombination frequencies between marker genes pa and we (1.9% +/- 0.3), we and un (8.8% +/- 0.5), and un and at (4.5% +/- 0.4) of strain B10.PA(L)-pa we un at. These strains and other Chr 2 congenic strains were typed for immunologically defined loci using monoclonal antibody (mAb) C23 reactive with the gene product of B2mb T-lymphocyte clone C1 reactive with the gene product of H-3a and H-3c, and lymphocyte clone H1.8 reactive with the gene product of Hd-1a. B2m and H-3 typing located a recombinational event separating [pa B2m H-3] from we (the order of bracketed genes is not known). Hd-1 typing indicated that Hd-1 maps distal to [H-42, H-44] and proximal to un. The gene order [pa, B2m, H-3], we, [H-42, H-45], Hd-1, un, H-13, at, with H-44 mapping centromeric to Hd-1, is indicated by the data.

Beta 2-microglobulin restriction of antigen presentation

Antigens are generally thought to be recognized by cytotoxic T lymphocytes as peptides in the context of class I major histocompatibility proteins complex, which are heterodimers of heavy chains noncovalently associated with beta 2-microglobulin (beta 2m). The highly polymorphic nature of the heavy chains and their resulting ability to present different sets of peptides has presumably evolved to allow potent immune responses against most pathogens. By contrast, the polymorphism of beta 2m is limited; seven alleles are known in the mouse and only one has been identified in humans. beta 2-Microglobulin was consequently thought to have only structural functions: namely, to ensure correct folding of class I molecules and their transport to the cell surface. Although beta 2m is not implicated directly in the formation of the peptide binding site, we report here that it participates in the selection of MHC class I molecule-associated peptides.

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.

Minor transplantation antigens: their role in shaping the T cell repertoire

Minor transplantation, or histocompatibility (H), antigens are the targets of host-versus-graft (hvg) and graft-versus-host (gvh) reactions that occur when organs or tissues are exchanged between members of the same species who, although genetically not identical, are matched for their major histocompatibility complex (MHC) encoded transplantation antigens. Genes encoding minor H antigens map outside the MHC, on a number of different chromosomes. Whilst gvh and hvg reactions against individual minor H antigens are relatively weak, certainly in comparison with such reactions against MHC antigens, the presence of multiple minor H differences (the situation encountered in man) gives rise to very vigorous reactions that can endanger the survival of graft or host, or both. This is the pathological role of minor H antigens and, indeed, it was this role which was first designated to the MHC antigens, before their physiological role as guidance molecules for T lymphocytes was discovered. Recently, a potential physiological role for minor H antigens has been uncovered by the finding that the presence of certain minor H alleles in mice leads to removal in the thymus (negative selection) of all those T cells expressing a particular T cell receptor (TCR) gene. Such cells therefore never reach the periphery, where they might otherwise give rise to autoimmune reactions. The T cell repertoire is thus moulded by at least some minor H antigens, which may therefore be regarded as non-MHC immune response genes. Furthermore, T cell receptor usage by T cells specific for allogeneic minor H antigens appears not to be representative of T cell receptor usage in the peripheral pool.(ABSTRACT TRUNCATED AT 250 WORDS)

H-Y responses of non-obese diabetic (NOD) mice

Female non-obese diabetic (NOD) mice were tested for their ability to make responses to the male-specific (H-Y) transplantation antigen. In vivo assessment of this ability was made using skin graft rejection. A proportion (60%) spontaneously rejected NOD male tail skin by 80 days post-transplantation. The detection of the generation of H-Y-specific cytotoxic T cells, following in vivo priming and secondary in vitro restimulation, was carried out using a conventional 51Cr release assay. Female NOD mice primed either by skin grafting, intraperitoneal (i.p.) or footpad (f.p.) injection of male NOD spleen cells could be induced to make anti-H-Y cytotoxic responses, but not every immunized mouse responded. The nature of the H-Y-reactive T cells was investigated further by the in vitro isolation of T-cell clones of which some were H-Y specific.

Unsuitability of the assay for cell-mediated lympholysis in inbred mice for H-Y antigen determination of human cells

This study examined the H-Y-specific in vitro restimulation of splenocytes from in vivo intraperitoneally (i.p.) primed C57B1/6 (B6) female mice. In vivo priming was carried out with human male or female fibroblasts or peripheral blood lymphocytes, respectively. It was attempted to measure the in vitro H-Y-specific activity by cell-mediated lympholysis and by cell proliferation. 3[H]Thymidine incorporation was determined in mixed lymphocyte cultures (MLCs) of xenogeneic primed female splenocytes (responder cells) and of syngeneic lethally irradiated male splenocytes (stimulator cells). The xenogeneic H-Y presentation by in vivo sensitization did not induce in the in vitro restimulation system an H-Y-specific cell proliferation or in the effector phase the generation of H-Y-specific killer cells. The assay for cell-mediated lympholysis and lymphocyte proliferation after xenogeneic priming and syngeneic in vitro restimulation is, thus, not suitable for H-Y testing of human cells.

Selective reversal of H-2-linked genetic unresponsiveness to lysozymes. II. Alteration in the T helper/T suppressor balance, owing to gene(s) linked to Ir-2, leads to responsiveness in BALB.B

Immune responsiveness to lysozyme in H-2b mice is under the control of H-2-linked Ir genes, with T suppressor (Ts) cells playing a dominant role in strains such as C57BL/6 (B6), C57BL/10 and A.BY. However, non-H-2-genes were found to be capable of specific reversal of the effect of the H-2-linked genes in responsiveness to chicken lysozyme (HEL), but not to human lysozyme (HUL). Therefore, studies were performed to identify any lesion in the suppressor circuit in BALB.B. It was known that HUL-induced suppressor cells could cross-suppress the anti-HEL response in B10.Q mice, which are responsive to HEL but nonresponsive to HUL. Similarly, BALB.B Ts cells were able to suppress the anti-HEL response, using as T helper (Th) source a T cell line (BB-1), derived from HEL-primed BALB.B periaortic and inguinal lymph node cells. A protocol designed to examine the in vivo suppression by the use of HUL-induced suppressor cells also demonstrated a significant suppression of the anti-HEL response. Since the suppressive circuitry seemed intact in the BALB.B, the possibility was examined that a step in T-B cell collaboration was more efficient in this strain than in the B6 nonresponder. With a B6-derived HEL-specific T cell line, BO1H, the B cell and antigen-presenting (B/APC) populations from B6 required addition of concanavalin A supernatant for anti-HEL antibody formation, whereas BALB.B B/APC were capable of responding to HEL in culture without the addition of concanavalin A supernatant. In agreement with this finding, when B/APC cell populations from BALB.B and B6 were compared for their extent of anti-HEL responsiveness, as measured with BB-1 Th cells, BALB.B B/APC populations responded significantly higher than B6 populations when the responses were activated by picogram/nanogram amounts of HEL. The response level of (BALB.B X B6)F1 B/APC measured in the same assay resembled that of B6. However, when HEL was used at the microgram level, both B6 and BALB.B strains responded equivalently. The above data are consistent with the expression of the reversing non-H-2 Ir gene(s) resulting from the balance of antigen presentation to Th and Ts cells in the H-2b mouse. In the B6, processing and handling of antigen may be inefficient in activating response-enhancing Th, and more effective in triggering Ts cells, while the reverse may be true for the BALB.B.

The cytotoxic T cell response to the male-specific histocompatibility antigen (H-Y) is controlled by two dominant immune response genes, one in the MHC, the other in the Tar alpha-locus

The genetic control of the cytotoxic T-cell response to the male histocompatibility antigen, H-Y, was analyzed in BALB/cKe(C) and SJL/J(J) which are both nonresponders. However, the (C X J)F1 hybrid is a responder. Therefore, two dominant complementing genes are involved. Analysis of a set of (C X J) recombinant inbred (RI) lines reveals that these two complementing gene products are a restricting element (R) encoded by the H-2 (MHC) locus on chromosome 17 and a subunit of the T-cell receptor (anti-R) encoded by the Tar alpha-locus on chromosome 14. The order and orientation of gene segments within the Tar alpha-locus has also been established relative to the chromosome 14 marker, Es-10. The existence of two RI strains which are recombinant at chromosome 14 has made it possible to determine that this order is Es-10--v alpha-1--v alpha-2--[C alpha--Np-2]--centromere. The implications of these data for the antigen-specific regulation of immune responsiveness are discussed in terms of the dual recognitive-single receptor model.

The role of H-2 and non-H-2 antigens and genes in the rejection of murine cardiac allografts

Genes of the major histocompatibility complex (MHC) in the mouse (H-2 complex) have been shown to be an important factor in determining the immune responsiveness of various strains of mice to isolated antigens (e.g., lysozyme). The role of MHC genes in controlling the responsiveness of mice to multiple alloantigens is less well-defined, and although non-MHC genes have been shown to be important in determining responsiveness in some systems (e.g., haptens), they have not been demonstrated as yet to influence the rejection of vascularized organ allografts. In this study, the responsiveness of mice to vascularized cardiac allografts transplanted across well-defined major (H-2) and minor (non-H-2) histocompatibility barriers was investigated using congenic mice in 32 different donor/recipient combinations. The results show that both H-2 and non H-2 gene products can act as target alloantigens for rejection. At the responder level, they may interact to effect responsiveness of a recipient strain to multiple alloantigens. In no case in this study has any one gene or group of genes been found to confer universal high or low responder status.

Complexity of minor histocompatibility loci

Allografts can be rejected as a result of major histocompatibility antigen disparity or as a result of differences at any of a number of minor histocompatibility antigens. In many cases, rejection due to multiple minor histoincompatibility is as difficult to control as that induced by major histoincompatibility. Although an understanding of the molecular, biochemical, and functional parameters of the major histocompatibility loci and their products is increasing at an exponential rate, little is known about these same facets of minor histocompatibility loci and their products. It is generally accepted that minor histocompatibility loci in the murine model have a degree of polymorphism similar to that of H-2K or H-2D. This conclusion was based on typing alleles by the classic F1-skin graft test. Based on these allelic assignments, numerous unexpected findings of CTL specificity were made. Therefore, a systematic analysis was made comparing CTL specificity, F1-complementation, and allograft rejection. Based on these three parameters, the data presented using strains of mice that were bred to, and therefore presumed to, differ only at H-3 indicate that the antigen disparity of these congenic strains and the parental B10 strain as defined by CTL specificity and skin graft rejection is much more complex than originally described. One especially interesting chromosomal region is H-3/beta 2-microglobulin in the fifth linkage group of chromosome 2. Using CTL, ten specificities are defined, three of which appear to be specific for beta 2-microglobulin-A, -B, and -C. These findings raise the question of whether any minor histocompatibility locus is polymorphic or is instead a composite of multiple minor H-loci which are masquerading as a single locus.

Female popliteal lymph node responses to H-Y antigen on male thymocytes in mice. I. Regulation of primary and secondary responses by H-2-associated Ir genes

H-2-linked genes which control popliteal lymph node (PLN) immune responses to the H-Y antigen were analysed. It was found that at least two genes or two groups of genes are involved in the genetic control and are responsible for the four variants of relations observed between the primary and the secondary response: +/-, +/+, -/+ and -/- ('+' and '-' stand for a high and a low response, respectively). The results obtained with H-2 recombinant haplotypes indicated that the genes controlling the primary and secondary responses map to the left and to the right of the E alpha locus, respectively. A high primary response was observed in the presence of b alleles at K, A beta, A alpha, and E beta loci, whereas a high secondary response occurred only in the presence of d alleles in the chromosomal segment between E alpha and D loci. From the experiments with F1 hybrids it is clear that low secondary responses are, for the most part, dominant and that the two seemingly separate control mechanisms for the primary and secondary responses may interact.

Determinant-specific regulation of T helper cell responses to murine lambda light chains by both H-2 and non-H-2 genes

Previous work has revealed that the T helper cell (Th) responses to an antigenic determinant of V lambda 2(315) (called lambda 2.1) is regulated by both H-2 and non-H-2 genes. In the present study this was confirmed and extended to two other determinants, one shared between free lambda 2(315) and lambda 1(J558) (called lambda 2.2) and one unique for free lambda 1(J558) (called lambda 1.1). H-2 genes regulate the responses to the latter determinants, because BALB.B (H-2b) mice were low responders and BALB/c (H-2d) mice were high responders. Thus, the H-2d haplotype on BALB/c background was associated with high responder status. However, when the H-2d haplotype was examined on other genetic backgrounds than BALB/c, the animals could be classified as either intermediate or low responders, depending upon the non-H-2 background. This demonstrated that non-H-2 genes also influenced Th responses. Furthermore, C3H-H-2o, DBA/2 and B10.D2 mice (all H-2d) responded to only one (lambda 2.1) but not the other (lambda 2.2) of two determinants physically linked on the same polypeptide chain (lambda 2(315)). This indicated that the non-H-2 gene effect is capable of fine discrimination, i.e. the non-H-2 gene-mediated low responder phenotype may at least in part be due to failure of recognition of certain antigenic sites, like the H-2-linked Ir-gene defect. F1 hybrids responded to the same determinants as their parental strains; e.g., the BALB/c non-H-2 background exerted a dominant influence over the low responder background of C3H, B10 and DBA/2 strains.

Immune response to the H-X antigen on P815-X2. I. Recombinant inbred strain analysis and lack of effect of castration

In a preceding report, the detection of an H-2-linked immune response to the H-Xd antigen on the P815-X2 mastocytoma was demonstrated by the significantly increased survival of (C57BL/6 X DBA/2)F1 (B6D2F1) male hybrids (H-Xb) compared with female siblings (H-Xb/H-Xd) after injection with the histocompatible tumor (H-Xd). This interpretation was supported by the absence of this sex effect in reciprocal D2B6F1 hybrids (H-Xd and H-Xd/H-Xb). Additional findings presented in this paper support the conclusion that this sex effect is due to a true immunological response to H-Xd: (a) Reciprocal (DBA/2 X C57BL/6 H-2 mutant)F1 hybrids, as well as D2B6F1, failed to exhibit the sex effect: (b) the demonstration of the sex effect in (BALB/c X DBA/2)F1 and (BALB/c-H-2dm2 X DBA/2)F1 hybrids and in (C57BL/10 X DBA/2)F1 hybrids was consistent with the known H-X incompatibilities between the strains BALB/c and DBA/2 and C57BL/10 and DBA/2, respectively, previously demonstrated by skin grafting; and (c) the sex effect was not abrogated by castration of male B6D2F1 hybrids. Variability in the presence or absence of the sex effect was observed in various [recombinant inbred (RI) X DBA/2]F1 hybrids and may be attributed to the influence of a regulatory non-H-2 gene which is closely linked to the gene coding for mouse kidney-androgen-regulated protein (KAP) but androgen-independent, or to variability in inheritance of the H-Xb allele among the RI lines. It is proposed that the P815-X2 model may be utilized to type RI lines derived from a cross between C57BL/6 and DBA/2 for their H-X genotypes.

Selective reversal of H-2 linked genetic unresponsiveness to lysozymes. I. Non-H-2 gene(s) closely linked to the Ir-2 locus on chromosome 2 permit(s) an antilysozyme response in H-2b mice

Genes outside of the mouse major histocompatibility complex (H-2) were found to be capable of specifically reversing the previously described nonresponsiveness to hen egg-white lysozyme (HEL) owing to H-2b immune response (Ir) genes. C3H.SW, BALB.B, and C57L, all of the H-2b haplotype, showed responsiveness to HEL, but not to human lysozyme (HUL). Mapping of the reversing gene(s) was attempted by testing H-2b recombinant inbred (RI) strains of mice carrying C3H, BALB, and C57L non-H-2 genes. Analysis of the strain distribution pattern of responsiveness with both CXB and BXH RI strains was consistent with the location of the responsible site within the H-3 region on chromosome 2. The anti-HEL proliferative responsiveness in two H-3 congenic strains of mice, B10.C(28NX)SN and B10.C-H-3cH-3a, that have BALB/c genes within the H-3 region confirmed the mapping, as well as localized the reversing gene(s) near the Ir-2 gene. The data are discussed with regard to the site of expression of the reversing gene(s) and its mechanism of action.

Review lecture. Immunology of H-Y antigen and its role in sex determination

H-Y was originally discovered as a transplantation antigen that caused female mice of certain inbred strains to reject skin from otherwise identical males. The ability to make the skin graft rejection response and, in vitro, cytotoxic T cell responses against H-Y is controlled by genes within the major histocompatibility complex, H-2, and by non-H-2 genes. H-Y belongs to a class of weak transplantation antigens characterized by an inability to elicit responses under many conditions. Although genetic factors are very important in determining responsiveness, their action can be modified by immunization procedures. H-Y has been proposed as the differentiation signal that causes the formation of the testes from the undifferentiated gonad in the developing embryo. This hypothesis has been explored by using a series of mice whose karyotype and phenotypic sex are paradoxical.

A lymphocyte antigen encoded by a locus closely linked to H-3 on the second chromosome of the mouse

A monoclonal antibody has been developed that recognizes a mouse lymphocyte antigen, Ly-23, that is controlled by an H-3 histocompatibility complex-linked gene on the second chromosome. Competitive binding experiments demonstrate that this antigen is distinct from the polymorphic beta 2-microglobulin antigen, which also is encoded by a gene closely linked to H-3. The strain distribution pattern differs from that of the beta 2-microglobulin polymorphism, and recombination apparently has separated the genes for these two antigens during the derivation of one recombinant inbred line. However, the R1E/TL8X line of cells, which lacks beta 2-microglobulin, is negative for the Ly-23 antigen, although the control R1.1 line is positive. The H-2 locus affects the expression of both the Ly-23 and beta 2-microglobulin antigens.