Studies on the specificities of two IgM lambda cold agglutinins.

The reactions of two monoclonal IgM lambda cold agglutinins, Sch and Sher, have been studied in detail with human and animal erythrocyte antigens. Although they were unusual in having lambda and not kappa polypeptide chains, they could be assigned to the anti I and anti-Pr1 groups of cold agglutinins. The findings with serum Sher indicated that the Pr1 antigen may be more complex than previously thought. The occurrence of unexpectedly large numbers of specificities among monoclonal anti-I, anti-i and anti-Pr antibodies is discussed and it is suggested that each monoclonal antibody may recognize only a limited portion of a complex red cell antigen.