Histocompatibility studies in pigs from outbred and semi-inbred families

Skin graft experiments with pig siblings from semi-inbred and outbred families confirmed the existence of a pig main histocompatibility system (MHS). Grafts exchanged between serological (lymphocytotoxicity) MHS incompatible siblings from outbred matings survived 5.6 days and between compatible animals 9.8 days. In compatible pairs from semi-inbred matings they survived 22.4 days and in incompatible individuals 6.1 days. Skin grafts exchanged between individuals with E blood group compatibility led to the formation of haemagglutinating and lym-phocytotoxic antibodies reacting with some E antigens. The results indicate that the survival of skin grafts in semi-inbred pigs is apparently influenced also by differences in the E system.