Interaction of L antibody with low potassium-type sheep red cells: Resolution of two separate functional antibodies

Summary Antibodies of two specificities in alloimmune sheep anti-L sera, anti-L_P and anti-L_l, were separated by a new technique and characterized. Absorption of anti-L serum with trypsinized LK (LL) sheep red cells left anti-L_P antibodies; the absorbed anti-L_l antibodies were then eluted. Anti-L_P was only weakly lytic in the presence of complement; it had no effect on passive K influx, but stimulated active K influx. The stimulation could be reversed by eluting the antibody in glycine buffer at low pH. Stimulatory activity in the eluted cells could be restored by resensitization with anti-L_P. Anti-L_l was more strongly lytic than anti-L_P in the presence of complement; it had no effect on active K influx, but inhibited passive K influx. Pig anti-ruminant IgG conjugated to hemocyanin was used to visualize by electron microscopy the number of L_P and L_l antigen sites onLL sheep red cells sensitized with anti-L_P and anti-L_l. The values obtained were 590 L_P sites/cell and 847 L_l sites/cell.