Comparison of haplotypes of the major histocompatibility complex in the rat. II. Serological analysis of the haplotypes H-1a (Ag-B4), H-1d (Ag-B9) and H-1f (Ag-B10).

The strongly cross-reacting haplotypes of the inbred strains DA, ACI, ACP, MR, BD V and AS2, and of the congenic lines LEW.1A, LEW.1D and LEW.1F, were explored. All of these inbred strains and these congenic lines type with anti-Ag-B4 antisera raised against the DA strain, which behaved as operationally mono-specific in previously reported studies of the eight currently defined Ag-B haplotypes. Serological analyses showed that this cross-reactivity was due to antibodies against public antigenic specificities which were not previously recognized as being in the anti-Ag-B4 antisera, due to the fact that the LEW.1D and LEW.1F animals were not available for testing. With the use of appropriate antisera and of absorption studies, two haplotypes in the H-1 system were found not to have been previously identified in the Ag-B system. The animals carrying the H-1d haplotype (MR, BD V and LEW.1D) have been designated as Ag-B9, and those carrying the H-1f haplotype (AS2 and LEW.1F) have been designated as Ag-B10. With the proper absorptions, an anti-Ag-B4 antiserum can be prepared which reacts only with the DA, ACI and ACP strains, and it will henceforth be used as the operationally mono-specific Ag-B4 typing reagent. A variety of typing experiments showed that the results using antisera raised in Pittsburgh and in Prague and using the Ficoll and dextran haemagglutination methods were the same.