In vitro induction of autologous T cell killing by heat treated human chronic myelogenous leukemia cells

Objective To investigate the potential of autologous T cell killing of heat treated chronic myelogenous leukemia (CML) cells (autologous tumor killing, ATK). Methods 51 Cr release assay was used to measure the ATK activity of autologous T cells against CML cells treated with 42?℃ for 30 minutes (heat) or 37?℃ for 30 minutes (non heat). The phenotypes of T cells and heat shock protein 70(HSP70) expression of CML cells were measured by flow cytometry (FCM). T cells from the CML patients were stimulated and expanded by autologous mixed lymphocyte/tumor cell cultures (MLTC). Results ATK activity of autologous T cells to the non heated and heated CML cells were found in 4 (19.05%) and 10 (47.62%) of the 21 cases, respectively. The ATK activity of interleukin 2 (IL 2) stimulated autologous T cells against heated CML cells was markedly higher than that of unstimulated autologous T cells against non heated CML cells (P0.001). FCM analysis showed that no HSP70 was expressed on the CML cell membranes whether heated or non heated, but intracellular HSP70 expressions were ( 83.42± 5.65)% and (78.34±6.32)% pre and post heated, respectively. The phenotypes of T cells stimulated and expanded in MLTC were TCRγδ- CD 3 +, mostly CD 8 +, with some activation markers (CD 25 and HLA DR) expression.The ATK activities of these T cells against the heated and non heated CML cells and K562 cells were (51 25±4.26)%, (36.52±3.83)% and (2.92±1.19)%,respectively. Conclusions ATK activity of autologous T cells against CML cells could be induced or enhanced by heat treatment of the CML cells. particularly of T cells stimulated with IL 2. This ATK activity was not associated with γδ T cells or HSP70 expression of CML cells.