Leukaemia-associated antigens in man. Detection by antibodies in maternal sera

A membrane antigen on peripheral blood lymphocytes from cases of chronic lymphatic leukaemia (CLL) is described. The antigen was detected by complement-dependent cytotoxicity using serum from a healthy pregnant woman, and appeared to be absent from the normal lymphocyte population in these patients. The serum was also cytotoxic for some acute leukaemia blast cells and for cultured Burkitt lymphoma cells; absorption studies suggested that the CLL antigen is identical to the acute leukaemic antigen. Similar antibody activity was also found in a number of HL-A typing antisera and could be separated from the HL-A specificity by absorption. Although these antibodies are probably directed against foetal antigens, the leukaemic antigen could not be demonstrated on foetal tissues.