Stimulation of B-lymphocyte colony formation in vitro by sera from patients with leukaemia or lymphoma.

Studies were made on the effects of 665 sera, from normal donors or patients with various diseases, on B-lymphocyte colony formation in agar by mouse spleen cells. Undiluted serum from most normal donors inhibited colony formation, but 43-53% of sera from patients with histiocytic lymphoma, lymphocytic lymphoma or Hodgkin's disease stimulated colony formation, serum activity correlating with the stage of the disease. Moderate colony-stimulating activity was observed with serum taken from patients with acute lymphoid or myeloid leukaemia following, but not prior to, chemotherapy. Colony stimulating activity was not correlated with the blood group of serum donors and could not be ascribed to the presence of endotoxin, red cells or mouse red cell haemagglutinins in the active sera. Elevated colony stimulating activity was not observed in sera from patients with non-neoplastic disorders ot haemopoiesis or with diseases of other organ systems.