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SUMMARY Polymorphism of the bovine DRB, DQA, DQB, DYA, DOB and DIB genes was investigated using restriction fragment length polymorphism (RFLP) analysis, isoelectric focusing (IEF), class II serology and polymerase chain reaction (PCR) based typing techniques. The simultaneous application of multiple typing techniques and the characterization of multiple genes resulted in a greatly enhanced picture of the bovine class II regions. Thirty-eight class IIa (DR-DQ) and 5 class lib (DYA-DOB-DIB) haplotypes were defined. It was found that IEF types were associated with DRB3 polymorphism defined by DRB3 PCR-RFLP and DRB3 microsatellite PCR. Serologically defined polymorphism was associated with distinct molecular/IEF motifs and, therefore, DR and DQ specificities could be tentatively distinguished. Although the DR and DQ genes are tightly linked, neither DR nor DQ typing defined all of the class IIa region polymorphism. Furthermore, even the most powerful DRB3 typing technique, DRB3 PCR-RFLP, failed to detect all expressed DRB3 polymorphism. All detected DRB3 polymorphism could, however, be distinguished with a combination of two molecular techniques: DRB3 PCR-RFLP and DRB3 microsatellite PCR. RFLP typing with transmembrane probes detected significantly less polymorphism than typing with cDNA or exon probes. However, the transmembrane probes were useful because they were locus specific. The presence of only 5 of 12 possible class lib haplotypes was unexpected and indicates that the DYA, DOB and DIB genes are tightly linked.

SUMMARY Lymphocytotoxic sera have been produced in forty-seven cattle following skin grafting or lymphocyte immunization between dam-offspring pairs. From these sera seventy antilymphocyte reagents have been produced. Seven of the sera were operationally monospecific without absorption, thirty-seven others were made operationally monospecific and twenty-six partially purified by absorption with lymphocytes. Thirty-five of these sera were used in France and an additional thirty-five were used in Scotland. The inheritance of the antigenic factors detected by these sera has been studied in 480 cattle families and the evidence is consistent with the hypothesis that at least seventeen of the factors are inherited in a simple Mendelian fashion. Fourteen of these factors show evidence of linkage with at least one other factor and are likely to be controlled by a limited number of closely linked loci. It is suggested that these loci should be identified as the BLA region.