Cold lymphocytotoxins in autoimmune haemolytic anemia

288 sera with red cell auto-antibodies and 141 control sera were investigated for cold lymphocytotoxins (CLCT). An incidence of 72% and 40% respectively was found in patients with cold haemagglutinin disease and in those with warm IgG type AHA. The absence of increased frequency in idiopathic or methyl-dopa induced asymptomatic red cell auto-immunization would suggest that CLCT might reflect an advanced degree of auto-immune disorder. No difference was observed in reaction patterns of isolated B and T lymphocytes or of those from individuals with I negative red cell phenotype.