Leukaemia-associated antigen in serum of patients with acute lymphoblastic leukaemia.

A antigen (HThy-L) previously found in extracts of human thymocytes and leukalphaemic cells was detected in sera from four patients with E-rosette-positive untreated acute lymphoblastic leukalphaemia (A.L.L.) and one patient with previously treated acute myelogenous leukaemia (A.M.L.) The disappearance HYth-L angignaplhaemia with treatment was coindent with a decrease in the number of leukaemic blast cells in the peripheral blood. HThy-L antigen was not detected in the sera of the remaining twenty-one patients with E-rosette-negative A.L.L. and seven patients with A.M.L..