The influence of homogeneous cold agglutinins on human B and T lymphocytes

Peripheral blood lymphocytes from healthy individuals, patients with Graves disease and with chronic lymphocytic leukemia, mixed tonsillary and purified B and T lymphocytes, and thymocytes were assayed for susceptibility to cytotoxic activity of cold agglutinins. Sera containing homogeneous anti-i and anti-I cold agglutinins as well as purified 19S IgM(K) anti-I cold agglutinin, and 7S, 11S, and 19S IgM(λ) anti-i cold agglutinins were used. A 2-hr bithermic cytotoxicity assay followed by E and EAC rosette was employed. Cold agglutinins killed and inhibited rosette formation of both B and T lymphocytes. Anti-i cold agglutinins were more lymphocytotoxic against normal peripheral blood, tonsillary and thymic lymphocytes, whereas anti-I cold agglutinins were more cytotoxic against peripheral blood lymphocytes from patients with chronic lymphocytic leukemia or Graves disease. Therefore, lymphocytes from various sources, both B and T, are susceptible to the cytotoxic activity of anti-i and anti-I cold agglutinins; however, the expression of Ii antigens seems to be variable.