Overshoot phenomenon of phytohemagglutinin response after chemotherapy and its relationship to remission in acute non-lymphocytic leukemia.

To define the relationship between cell-mediated immunity and responses to chemotherapy or prognosis, delayed cutaneous hypersensitivity, E- and active E-rosette tests, and mitogenic responses of lymphocytes were examined in 15 patients with acute nonlymphocytic leukemia. Its results indicated that cell-mediated immunity before remission induction chemotherapy did not correlate with the outcome of treatment. In contrast, delayed cutaneous hypersensitivity and mitogenic response tested after remission induction correlated with therepeutic effect. Further a "rebound" or overshoot of phytohemagglutinin responsiveness was observed in patients achieving remission. Serial studies on cell-mediated immunity may be useful for predicting therapuetic efficacy and prognosis in patients with acute leukemia.