Acute promyelocytic leukaemia: further evidence of the differentiation-linked expression of Ia-like (p28,33) antigens on leukaemic cells.

Patients with acute non-lymphoblastic leukaemia were studied to determine if the presence of Ia-like antigens on leukaemic cells was related to the maturity of a leukaemic cell line. Ia-like antigens were present in the majority of acute myeloblastic and myelomoblastic leukaemias. 4 patients with acute promyelocytic leukaemia were Ia-negative. This finding suggests that Ia-like antigens reflect normal differentiation linked events in haemopoiesis. The presence of Ia-like antigens on leukaemic cells did not alter the patient's response to chemotherapy.