The M-L blood group system and its influence on red cell potassium levels in sheep

Five phenotypes within the M-L blood group system of sheep were identified with three reagents: anti-L(m), anti-M and anti-M'. Factor M' only occurred in combination with M. The serological properties were studied and the potassium concentrations in the red cells of the various phenotypes were compared. Like M, the L antigen was only weakly developed on the red cells of newborn lambs, and it was only when adult low potassium levels were established that full L activity was reached. These results support the hypothesis that antigen L is acting as an inhibitor of active potassium transport.