Genetic definition of I region‐determined antigens of the rat major histocompatibility complex

摘要

AbstractA recombinant haplotype of the major histocompatibility complex (H‐1) of the rat has been found among F2hybrids of two congenic strains, and it has been shown previously that the major gene determining mixed lymphocyte stimulation and the Ir‐TGAL and Ir‐PheGAL genes were separated from the genes determining the classical serologically detectable histocompatibility antigens. It has been shown that the complementing Ir‐HGAL genes mapped together with the other Ir genes, and this gene cluster is assumed to represent the I region of the rat. Serological analysis of the recombinant is interpreted as showing that the Ir genes do not map in‐between the genes controlling the classical histocompatibility antigens. Thus, the sequence of the major histocompatibility genes in the rat does not seem to follow that of the mouse H‐2 system. Reciprocal immunization between the recombinant and the parental strain which shares the classical transplantation antigens but differs for the Ir genes, led t o the production of antisera which detected antigens with restricted tissue expression. These antigens were predominantly found on B lymphocytes and not on liver, brain or red blood cells and thus resembled mouse Ia antigens. Strain distribution analysis revelaed extensive cross‐reactivity with most of the H‐1 haplotypes, and two private specificities could be operationally defined. Thus, it is now possible to genetically define Ia antigens in the rat by the use of I region