Importance of different regions of H-2 for MLC stimulation.

The major histocompatibility complex (MHC) in the mouse is the strongest barrier to allograft survival. One measure of MHC disparity is the mixed leuk,ocyte culture (MLC) test in which lymphocytes from a potential recipient strain, respond to mitomycin C treated lymphocytes of a different donor strain, for example, in the mixture ABm. The MHC in the mouse can be divided into four different regions (from left to right) (Klein & Shreffler 19172): the H-2K region characterized by the H-2K locus, alleles of which determine serologically defined (SD) antigens; the immune response ( I r ) region which includes at least two loci determining immune responsiveness ( McDevitt & Benacerraf 1972, Lieberman & Humphrey 1972); the Ss region marked by the Ss-Slp locus (Passmore & Schreffler 1970); the H-2D region in which the H-2D locus determines a series of SD antigens. Recent evidence which we have obtained suggests that the strongest MLC activation in the mouse is associated with MHC dis-