Inhibiting effects on the induction of cytotoxic T lymphocytes by dendritic cells pulsed with lysates from acute myeloid leukemia blasts.

Dendritic cells (DCs) were established from 25 patients in complete remission of acute myeloid leukemia (AML). In patients during hematopoietic regeneration following chemotherapy the yield of DC was comparable to that of healthy donors. In patients, more than 2 months after chemotherapy, significantly less DC were generated. Comparison of the antigen-presenting capacity using tetanus toxoid of six AML patients and six healthy volunteers did not show significant differences. In six AML patients, lymphocytes stimulated with blast cell lysate pulsed DC were analyzed for cytotoxic activity against autologous blast cells. 8.4-35.6% of autologous blast cells were lysed by DC stimulated lymphocytes. In three of the six patients maximum lysis of target cells was achieved by unpulsed DC. Thus, it seems that in some patients blast cell lysates mediate inhibitory effects, which may explain to some extend immune escape mechanisms in AML.