SLB, a new alloantigenic system of the pig.

An alloantigen segregating in the double back-cross families, distinct from serologically determinalble transplantation antigens controlled by the major histocompatibility complex (SLA), was detected in pigs by the complement-dependent lymphocytotoxic technique. The system was designated SLB and its product (antigen SLB-A1) was demonstrated in all lymphocytes from the lymph nodes, thymus and peripheral blood, but not in the erythrocytes. Back-cross matings supplied evidence of the dominant heredity of SLB-A1. Detection of further SLB antigens was unsuccessful, so that only two alleles (SLB-A1 and SLB-A-) could be determined in families. Double back-cross families revealed a close linkage between the SLB locus and the L blood group locus. Maximun lod score values were calculated in recombination fraction theta=theta.10.