Cytotoxic T-cell responses to H-Y:Ir genes and associative antigens map inH-2

A new cytotoxic lymphocyte-defined antigen coded by a gene closely linked to the H-3 locus

F1 complementation results indicate that a new gene, putatively controlling a minor histocompatibility antigen, is closely linked to the minor histocompatibility gene, H-3, in the fifth linkage group of chromosome 2 of the mouse. This gene controls a product that was capable of inducing as well as acting as a target for cytotoxic lymphocytes (CTL). The lytic activity of CTL developed in B10.LP-H-3D mice specific for the product of the new gene of B10 was restricted to target cells possessing H-2Db antigens. This contrasts to the H-2Kb-restricted activity of H-3.1 specific CTL.

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.

Gender differences in autoimmune demyelination in the mouse: implications for multiple sclerosis

Gender-related differences in experimental allergic encephalomyelitis (EAE) were examined in the SJL mouse with the purpose of characterizing an animal model ideal for the study of gender-related differences in multiple sclerosis (MS). For the model to allow for study of the induction and the effector phase of disease, the adoptive EAE model was characterized. First, the SJL strain was shown to be nonresponsive with regard to the development of antisyngeneic HY-specific responses in females, thereby permitting intergender adoptive transfers of T lymphocytes during EAE induction. Then, when myelin basic protein (MBP)-specific T cells derived from females were adoptively transferred into female and male recipients, female recipients demonstrated a more rapid onset of disease (p = 0.01), greater maximal acute-phase clinical scores (p < 0.0001) and greater mean clinical scores (p < 0.0001) compared with male recipients. When MBP-specific T cells derived from males were adoptively transferred, female recipients again tended to be more severely affected. Histopathologic analysis revealed quantitative differences between genders that paralleled clinical expression. These results document a clear gender-related difference in adoptive EAE in the SJL, with clinical and histopathologic disease greater in females compared with males. This model will be a useful tool for addressing autoimmune mechanisms underlying gender-related differences in MS.

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.

T helper cell lines that augment in vivo cytotoxic T-cell responses to minor alloantigens

We have investigated the ability of long-term cultured T helper (Th) cell lines to help an in vivo cytotoxic T lymphocyte (CTL) response to non-H-2 alloantigens (minor antigens). Th cell lines specific for various single or undefined minor antigens were selected by regular restimulation with antigen in vitro. They were antigen specific and H-2 restricted in proliferation assays and were found to be able to help primary CTL responses to multiple minor antigens and secondary CTL responses to single minor antigens. Although the Th were antigen specific they did not determine the specificity of the CTL. Th cells were both necessary and limiting for an effective CTL response indicating that "helper-independent" CTL are not in themselves sufficient to generate a strong in vivo response. Under conditions where a CTL response was clearly H-2 restricted, Th cells were not. Thus, the Th cells appeared to be activated by reprocessed antigen rather than antigen on the surface of the injected antigenic cells even though the CTL themselves reacted directly to the injected antigen.

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.

The recognition of abnormal sex chromosome constitution by HLA-restricted anti-H-Y cytotoxic T cells and antibody

Using the cell-mediated lympholysis (CML) technique, we studied lymphocytes of six individuals with discrepancies between the karyotypic and phenotypic sex. Two sets of cytotoxic T cells (CTLs) obtained from two multitransfused female aplastic anemia patients were used as typing reagents. These cells were previously shown to kill allogeneic target cells from HLA-A2- or B7-positive male donors. An antiserum obtained from one of the patients likewise killed HLA-A2 male lymphocytes. The six patients studied were selected for the required antigens. Positive reactions were obtained with lymphocytes from a 46,XY woman with pure gonadal dysgenesis and a 45,XO male. Target cells of the mother of the latter patient were also lysed. One individual with a 45,XO/46,X,del(Y)? karyotype was weakly positive, while three 46,XX males were completely negative. The reactivity of the HLA-A2-restricted H-Y-specific antibody showed the same discriminatory patterns. The results obtained by the HLA-restricted CTLs as well as by the antiserum did not correlate with the presence of testes as is the case in a different test system for the serologically detectable male (SDM) antigen in man. On the other hand, there was a correlation with the presence of cytologically detectable Y-chromosome material in five of the six individuals studied. The HLA-restricted CTLs and the antibody might recognize the classical transplantation antigen H-Y.

The role of H-Y as a minor transplantation antigen

H-Y antigen is expressed in mammals only by males, so that grafts of male tissue are rejected by females within certain highly inbred strains. H-Y antigen appears to be a simple, non-polymorphic antigen and the genetic control of anti-H-Y responses has been extensively studied. In this article Elizabeth Simpson discusses the many insights obtained.

HLA restriction of dinitrophenyl-specific cell-mediated cytotoxicity in vitro

Lymphocytes from dinitrochlorobenzene-sensitized individuals can be stimulated in vitro by autologous dinitrophenyl (DNP)-conjugated lymphocytes to produce cytotoxic T lymphocytes (CTLs). The activity of these CTLs is specific for DNP-conjugated target cells, and there is no cross-reaction with nitrosodimethylaniline- or trinitrophenyl-conjugated target cell. Evidence is presented which makes it improbable that the cytotoxicity is caused by an antibody-dependent (ADCC-like) mechanism. Most of the DNP-specific cytotoxicity is restricted by the HLA-ABC antigens of th CTL donor, and there is only a low degree of lysis of DNP-conjugated allogeneic target cells not sharing HLA-ABC antigens with the donor. The CTLs did not lyle non-conjugated allogeneic target cells. When CTLs were tested against allogeneic DNP-conjugated targets sharing only one of the HLA-ABC antigens of the CLT donor, it was seen that the phenomenon of preferential restriction was pronounced; that is, only some of the antigens of the donor were restricting. A certain pattern has emerged: some antigens (e.g. A2) are good restricting antigens, some (e.g. B12) do not restrict, and some (e.g. B5) function well in one donor but not in another. The serologically cross-reacting antigens A2 and A28 did not restrict mutually. HLA-C antigens may in some donors function as restricting antigens.

Delayed-type hypersensitivity responses to H-Y: characterization and mapping of Ir genes

This paper examines the delayed-type hypersensitivity (DTH) response to male (H-Y) antigen(s). Female mice of the H-2b haplotype developed delayed footpad reaction to syngeneic or allogenic male thymus and spleen cells after priming with syngeneic male thymus and spleen cells. The reaction peaks at 24 h, has classical DTH histology and is specific to H-Y antigen as it is not elicited with female cells. Cell transfer studies show that donor/recipient matching at the I-Bb subregion is necessary for successful transfer of DTH and that the effective primed population is Thy-1+, Lyt-1+, 2-. DTH response to H-Y antigen appears to be confined to mice of the H-2b haplotype. There appears to be a lack of associative recognition between H-Y antigen and MHC-coded determinants in the effector phase of DTH, and macrophage processing of H-Y seems likely, since nonresponder haplotypes can elicit the DTH response. Studies with H-2b recombinant mouse strains indicate that the dominant Ir gene is located in the I-B region. Female F1 hybrid mice derived from matings of strains not involving H-2b haplotype failed to develop DTH to H-Y. In summary, these data imply that a complete correlation exists between DTH to H-Y and the ability to reject male skin graft, suggesting that the effector mechanisms of skin-graft rejection may closely involve DTH cells.

Quantitative variation in H-2-antigen expression. II. Evidence for a dominance pattern in H-2K and H-2D expression in F1 hybrid mice

Further evidence for quantitative variation in H-2-antigen expression in F1 hybrids is described. Spleen cells from nine different F1 hybrids were compared with parental strain cells for differences in H-2K- and H-2D-antigen expression by quantitative absorption analysis and in an 125I-radioimmunoassay using anti-H-2 sera. Some K and D antigens are expressed in two to three times smaller amounts in F1 hybrids, while others are approximately equally expressed. There was no evidence for either I-region control or parental influence in the genetic control of H-2-antigen expression. Expression of K and D antigens in an F1 hybrid (compared with parental cells) is dependent on the K and D allelic composition of the hybrid, in that some alleles tend to dominate over others. In four different F1 hybrids, Kk was more strongly expressed than Kb, while, in other F1 hybrids, Kd predominated over both Kk and Kb. Similarly, Db dominated over Dd in five different F1 hybrids, while no obvious dominance pattern was found in F1 hybrids carrying Dk.

Three-receptor, clonal expansion model for selection of self-recognition in the thymus

The postulate is made that dual recognition by T lymphocytes is due to two types of receptor, one encoded by antibody genes and one by a distinct multigene family with simple rules for expression. This postulate leads to a model explaining ontogenic and evolutionary selection for self recognition, T lymphocyte effector function, the apparent high frequency of alloreactive T cells and immune response gene activity. The model is contrasted with previous explanations of self-recognition phenomena.

Time-dose-response studies on cellular immunity

The time-dose responses to several murine histocompatibility antigens were studied using lymphocytes as an antigen source for immunization and the speed of rejection of skin grafts as an assay of the level of immune responsiveness. It was observed that the weaker the first set response to an antigen the higher the minimal immunizing dose and the lower the tolerizing dose; thus, there was a small "immunizing window." The speed of onset of immune responsiveness and the magnitude of change in it following first antigen contact depended on the "strength" of the antigen. When the antigen was "strong" the level of response increased rapidly following first antigen contact. When the antigen was "weak" a period of tolerance appeared following first antigen contact, which then gave way to a state of immunity; the "weaker" the antigen the longer the interval and the greater the magnitude of tolerance. Increasing the antigen dose tended to magnify and prolong the tolerance. The "weaker" the antigen the longer the interval between first antigen contact and the appearance of immunity. Once established, the level of immunity was not constant. Undulations in the levels of all responses were noted; the "weaker" the antigen the larger the undulations. Possible explanations for the undulations and implications of the time-dose-response curves in immunotherapy are discussed.

Murine cytotoxic T-cell response to alphavirus is associated mainly withH- 2D ( k )

A secondary in vitro response to alphaviruses Bebaru, Sindbis, and Semliki Forest is described. Optimum response appears at day 5-6 of culture. The cells responsible for lytic activity are nonadherent, Φ-positive, Ig(-), and mainly Ly-2.1 positive. Out of five haplotypes tested (H- 2 ( d ),H- 2 ( b ),H- 2 ( s ),H- 2 ( q ), andH- 2 ( k )) onlyH- 2 ( k ) was a responder. Genetic mapping of the response located it solely in theD region of theH- 2 complex. The other four haplotypes responded with a high antiself activity after a second stimulation with viruses. This antiself response also maps in theD region of theH- 2 complex. No complementation was observed in F(1) hybrids between responder and nonresponder strains.

Anti-H-Y responses of H-2b mutant mice

Two strains of H-2b mutant mice, H-2ba and H-2bf, in which the mutational event took place at H-2K, make anti-H-Y cytotoxic T cell responses which are H-2-restricted, Db-associated and indistinguishable in target cell specificity from those of H-2b mice. Thus, alteration of the H-2K molecule affects neither the Ir gene controlling the response, nor the associative antigen. On the other hand, one H-2Db mutant strain, H-2bo, although it makes a good anti-H-Y cytotoxic response, shows target cell specificity restricted to its own Dbo antigen(s), and neither H-2b, H-2ba or H-2bf anti-H-Y cytotoxic cells kill H-2bo male target cells. Thus, the alteration of the H-2Db molecule does not affect the Ir gene of H-2b mice, but it does alter the H-2Db-associative antigen.