The M-L blood group system and active potassium transport in sheep reticulocytes

Immature and mature red cells from anaemic homozygous and heterozygous low potassium (LK) type sheep were tested for the presence of the L antigen and for active potassium uptake. Evidence was obtained for the presence of L antigen on immature as well as mature cells, but immature cells had a higher intracellular potassium concentration and increased rate of active potassium transport which was only slightly enhanced after sensitization with L antiserum. The red cells which entered the circulation in the later phases of recovery from anaemia were not haemolysed by anti-L as readily as normal cells, but showed normal haemolytic reactions with other blood typing reagents.
It is suggested that, if the L antigen is directly concerned with suppressing part of the potassium pump in mature LK erythrocytes, its effect must be mediated by changes which occur during the final maturation processes of the red cell.