Of cows and men: a comparative study of histocompatibility antigens

Bovine histocompatibility antigens cross-react highly with HLA antigens in comparison to their homologues in other nonprimate species. A panel of 34 anti-HLA monoclonal antibodies was tested for binding activity with lymphocytes from five breeds of cattle. Eleven antibodies demonstrated extensive cross-reactivity. Lymphocytes from several species of ungulate and subungulate were then tested with the same panel of antibodies. The buffalo and hyrax also displayed some cross-reactivity, though not as extensive as seen with the cattle lymphocytes. Other ungulates showed essentially no cross-reactivity. The significance of these results is discussed in terms of the structure and evolution of histocompatibility antigens.