HOMOLOGIES BETWEEN THE MAJOR HISTOCOMPATIBILITY COMPLEX OF MAN AND CATTLE - CONSEQUENCES FOR DISEASE RESISTANCE AND SUSCEPTIBILITY

The major histocompatibility complex (MHC) of mammals contains a large number of mostly duplicated genes. In the HLA system (the MHC of man), which is by far the best-studied major histocompatibility system so far, roughly 20 genes have been defined and mapped. They code for three classes of proteins: HLA-A, -B and -C (Class I), HLA-DP, -DQ and -DR (Class II) and serum complement components C2, C4 and Bf (Class III). Furthermore, the region contains genes for 21-hydroxylase (21-OH) and tumor necrosis factor (TNF). The MHC thus forms a chromosomal segment containing several clusters of genes of only partially defined biological significance, but ondoubtedly playing a role in disease susceptibility. In view of the recently obtained structural information on BoLA, the MHC of cattle, it is hypothesized that susceptibility to diseases in cattle is associated with BoLA in the same way as human diseases. Finally, new technical and conceptual developments in the field of MHC research and their application to the BoLA system are discussed.