Cell-mediated Lympholysis of Trinitrophenyl-modified Autologous Lymphocytes

The major histocompatibility complex (MHC)' has been shown to play an important and probably essential role in the immune systems of a number of animal species ranging from mouse to man (1-3) . The murine MHC known as the H-2 complex has been divided into four major regions, and include two serological regions known as H-2K and 11-21) or K and D, which are separated by two other regions designed I and S (4) . The K and D regions determine the strong serologically detectable transplantation antigens of the mouse, which seem to be important as the target antigens for T-cell-mediated lympholysis (5-10) . The S region is positioned adjacent to and to the left of the D region with respect to the centromere . It determines the levels of a serum alpha globulin known as Ss as well as a sex-linked allotypic variant of Ss designated Slp (11) . Genes mapping within the I region designated Ir or immune response genes, are located between K and S, and control immune response potential to a number of synthetic and natural immunogens (for review see 12-14) . Recent Ir-gene (15-17) and Ia-antigen (18-21) studies in B10.A recombinant mouse strains have led to the division of the Iregion into three regions designated I-A, I-B, and I-C (22) . At the present time, therefore, the H-2 complex is clearly divisible into six regions: K, I-A, 1-13, I-C, S, and D. Some of the immunological functions attributed to MHC genes have been demonstrated by employing allogeneic grafting or cell combinations between incompatible partners . Although such procedures are necessary for detecting alloantigens, it is unlikely that these immunological phenomena as well as the antigenic differences they reflect were naturally selected in evolution for the purpose of allogeneic immune reactions .