H-Y antigens

H-Y antigen is defined as a male histocompatibility antigen that causes rejection of male skin grafts by female recipients of the same inbred strain of rodents. Male-specific, or H-Y antigen(s), are also detected by cytotoxic T cells and antibodies. H-Y antigen appears to be an integral part of the membrane of most male cells. In addition, H-Y antibodies detect a soluble form of H-Y that is secreted by the testis. The gene (Smcy/SMCY) coding for H-Y antigen detected by T cells has been cloned. It is expressed ubiquitously in male mice and humans, and encodes an epitope that triggers a specific T -cell response in vitro. Additional epitopes coded for by different Y-chromosomal genes are probably required in vivo for the rejection of male grafts by female hosts. The molecular nature of H-Y antigen detected by antibodies on most male cells is not yet known. Testis-secreted, soluble H-Y antigen, however, was found to be identical to Müllerian-inhibiting substance (MIS). MIS cross-reacts with H-Y antibodies and identical findings were obtained for soluble H-Y antigen and MIS, i.e., secretion by testicular Sertoli and, to a lesser degree, ovarian cells, binding to a gonad-specific receptor, induction of gonadal sex reversal in vitro and, in cattle, in vivo. H-Y antisera also detect a molecule or molecules associated with the heterogametic sex in nonmammalian vertebrates. Molecular data on this antigen or antigens are not yet available.     

Interactions of tumor-associated fetal antigens with rat histocompatibility antigens

The physical interactions of fetal antigens (tumor-associated fetal antigens; TAFA-I, TAFA-II, and TAFA-III) with rat histocompatibility antigens were studied. TAFA-I and TAFA-III are present on syngeneic (NBR) and allogeneic (Fisher F344, Wistar Furth, and White Buffalo) rat embryo fibroblasts and on tumor cells. TAFA-II was found only on NBR (syngeneic) rat embryo fibroblasts and on NBR tumor cells. Antibody-blocking experiments were used to examine the fetal and histocompatibility antigen topography on cell membranes of tumor cells transformed by chemical and viral carcinogens. Precoating the tumor cells with alloantisera inhibited the subsequent adsorption of anti-NBR embryo, anti-TAFA-I, and anti-TAFA-III sera, but not anti-TAFA-II serum. Immunofluorescent cocapping experiments indicated that TAFA-I and TAFA-III, as well as other fetal antigens found on cells from 14-day gestation NBR embryos cocap with histocompatibility antigens when tested on syngeneic embryo fibroblasts and on sarcoma cells. TAFA-I cocapped with White Buffalo (Buf) strain rat histocompatibility antigens on herpes simplex Type II virus-transformed cells. The specificity of the TAFA-histocompatibility interactions was confirmed by demonstrating that the different anti-TAFA sera did not have contaminating antiviral antigen specificity; and also that these interactions did not occur on normal adult fibroblasts or spleen cells.     

Relationship of F9 antigens to spermatogenic cell antigens

Mice immunized with teratocarcinoma F9 cells or human blood group substances A, B or H exhibited significant inhibition of spermatogenesis comparable to the inhibition induced by immunization with testicular cells. All these immunization schemes resulted in the production of antibodies which recognize antigens common to F9 and spermatogenic cells. In addition to these antigens, both anti-F9 and anti-ABH sera also recognize antigens which are specific for F9 cells. One of them was identified as SSEA-1. These results support the hypothesis that oncofetal F9 antigens are carbohydrate structures, which may play an important role in spermatogenic cell differentiation.     

Bacterial capsular antigens. Structural patterns of capsular antigens

Structural patterns of bacterial capsular antigens including capsular polysac charides and exoglycans are given in this review. In addition, the immunological activity of capsular antigens and their role in type specificity of bacteria are discussed. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 9, pp. 115–1174.     

Bovine leukocyte antigens

Using bovine erythrocyte typing reagents in a leukocyte microcytotoxicity system, bovine peripheral blood leukocytes were found to have specific surface antigens. In this study, no obvious association between leukocyte.antigens and erythrocyte antigens of any individual animal was found. The leukocyte and erythrocyte antigens appeared to be distinct from each other.     

Antigenic differences between tumor-associated fetal antigens and rat histocompatibility antigens

Certain molecular properties of purified tumor-associated fetal antigens (TAFA) were analyzed by sequential immune precipitation (SIP), isoelectric focusing, and high-pressure liquid chromatography (HPLC). The antigenic relatedness of rat histocompatibility antigens and the various TAFA were determined by SIP. SIP of chloramine-T-labeled purified TAFA or lactoperoxidase-iodinated tumor cell membranes, in the presence of rat alloantisera and monospecific rabbit anti-TAFA sera demonstrated no antigenic cross-reactivities or similarities between H-antigens and TAFA. TAFA were also compared with histocompatibility antigens for isoelectric point optima and molecular weight. Rat H-antigens had isoelectric points in the 7.0–8.5 pH range, whereas all TAFA focused at pH 5.0–6.5 or above pH 8.0. Molecular weights were determined by HPLC. TAFA-I and TAFA-III had molecular weights of 16,000–17,500 daltons, whereas TAFA-II had a molecular weight of 12,000. The antigens were not coprecipitated by the rat alloantisera. Each TAFA was also isolated (via immune precipitation) from NP-40-solubilized tumor cell membranes. These TAFA were identical to the chloramine-T-labeled TAFA which had been previously extracted and purified from rat fibrosarcomas and osteosarcomas. These studies demonstrated that although TAFA and H-antigens cocap on embryonic and transformed cell membranes, these determinants are different molecules; they are not covalently linked on cell membranes; and TAFA are not cleavage products of normal NBR H-antigens.