Abstract Thus far, the rat major histocompatibility complex (MHC), AgB or RTI, have been divided by recombinational analysis into two regions, AgB.A (RTI.A) coding for transplantation antigens (class I gene products) and AgB.B (RTI.B) controlling the humoral immune response (Ir genes) and the proliferative response to allogeneic cells (MLR, class II genes). In this study, an attempt was made by biochemical analysis to determine whether there exists more than one AgB.A (class I) gene product, as has been found in the mouse (H-2K and H-2D) and in the human (HLA.A and HLA.B antigens). NP40-solubilized 3H-fucose-labeled rat MHC membrane products were immunoprecipitated and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Firstly, with a congenic anti-erythrocyte serum, only membrane structures with an approximate m.w. of 45,000 (AgB.A) were precipitated. A congenic anti-lymphocyte serum absorbed with erythrocytes precipitated antigens with an apparent m.w. of 33,000 and 28,000 (AgB.B) whereas the unabsorbed serum precipitated in addition a 45,000-dalton component (AgB.A). Secondly, sequential treatment of a DA (AgB4, RTIa) extract with a strongly cross-reactive serum followed by an (Lewis × BN.B2)F1 anti-AgB4-specific serum demonstrated that the AgB4 haplotype codes for at least two AgB.A and at least two AgB.B gene products.
Soluble HL-A antigen extracted from cultured human lymphoid cells (RPMI 1788, HL-A 2, 10, 7, W14) by the 3M KCl method was injected into rabbits. The rabbit anti-HL-A sera contained antibodies against all the HL-A specificities present on the immunogen. Moreover, these same xenoantibodies reacted also with certain murine lymphocytes bearing distinct H-2 specificities in the direct complement dependent lymphocytotoxic test. Absorption studies confirmed this selected reactivity and led to the conclusion that mainly antigenic determinants of the D region of H-2 d and the K region of H-2 b are involved in this cross-reactivity. Rabbit anti-HL-A sera absorbed with cells of different mouse strains were tested against a large panel of human lymphocytes from unrelated donors for remaining cytotoxic activity. The results indicate that absorption with cells of the genotypes H-2 b (K b D b ) and H-2 a (K k D d ) remove antibodies against determinants of the first segregant series (cross-reacting with HL-A 2 and 10). These data suggest a specific cross-reactivity between human and murine histocompatibility antigens and suggest a certain structural homology between these cell surface antigens and perhaps even a similar organization of the genetic fine structure of the HL-A and H-2 systems.
Different methods for determination of T-lymphocytes in human peripheral blood were compared: rosetting with sheep erythrocytes (SRBC), AET-treated SRBC, immunofluorescence using a monoclonal antibody against T cells (BL-T2), complement dependent cytolysis with polyclonal antisera against thymocytes, cytochemical demonstration of unspecific acid alpha-naphthyl-acetate esterase (ANAE), and electrophoretic mobility using a cell electrophoresis system (PARMOQUANT 2). Depending on the method, mean values between 70 and 79% T cells among separated mononuclear cells (MNC) were found. All paired observations were subjected to statistical analysis using rank correlation and U-test. From this analysis it is concluded that rosetting with SRBC, immunofluorescence using the monoclonal T-cell antibody and cytochemical reactivity for ANAE are favored methods for determining the T cell content of human MNC. However, the monoclonal antibody BL-T2 and the ANAE are not generally applicable because both markers were also found on malignant B-lymphocytes (B-CLL).