Lysis of autologous tumor cells by large granular lymphocytes in patients with acute leukemia in complete remission: Correlation between lytic activity and clinical outcome

In order to evaluate the effect of specific immune response on prognosis in acute leukemia, we investigated the correlation between the lysis of autologous tumor cells (ATC) by lymphocytes and prognosis. Peripheral mononuclear cells (PMC) from most patients with acute leukemia in complete remission (CR) do not exhibit cytotoxic activity against fresh-frozen ATC, although they have adequate cytotoxic activity against K562 cells. When the large granular lymphocyte (LGL) fraction was used in this study, we observed lysis of ATC in 17 (43.6%) of 39 patients with acute leukemia (12 (42.9%) of the 28 patients with acute myelogenous leukemia (AML) and 5 (45.5%) of the 11 patients with acute lymphocytic leukemia (ALL)). With regard to prognosis, the lytic activity of the LGL fraction did not reflect the duration of CR. The median CR duration in AML patients was 13 months for the lysis-positive group and 11 months for the lysis-negative group. No significant correlation was also found between lytic activity of the LGL fraction and overall survival in each patient. However, the lysis-positive group tended to have a longer survival, the median overall survival being 48 months for the lysis-positive group vs 12 months for the lysis-negative group. The prolonging of overall survival in the lysis-positive group was attributed to a high rate of induction of second remissions in this group. Long-term patient survival in the two groups did not differ.