Expression of Fas antigen in acute myeloid leukaemia is associated with therapeutic response to chemotherapy

Flow cytometric immunofluorescent analysis was used to assess Fas antigen (CD95) expression in blasts obtained from the bone marrow of 30 patients with acute myeloid leukaemia. The percentage of positive cells in each sample was highly variable. Fas antigen expression did not correlate with age, FAB subtype, white blood cell counts, or CD34 expression. Low expression of Fas was associated with a low complete remission rate after induction chemotherapy (62.5% in cases with <20% positive cells v 92.9% in cases with ≥ 20% positive cells, P<0.01). The main cause for not achieving remission was resistant disease. Our results suggest that the quantitation of Fas expression can be predictive of treatment outcome in acute myeloid leukaemia.