Sensitivity of ovarian tumor cells to effector cells generated by various biological response modifiers

The sensitivity of freshly derived human ovarian tumors (FOT) to various allogeneic cytotoxic effector cells stimulated by recombinant interleukin 2 (rIL-2), recombinant interferon alpha 2 (rIFN-alpha 2), OK-432, and concanavalin A was examined using the 51Cr release assay. Peripheral blood lymphocytes (PBL) of normal female donors were used as source of effector cells. Incubation of PBL with these biological response modifiers for 24 h generated effector cells with high natural killer activity, and only 20% (1/5) of the FOT examined were susceptible to lysis. By contrast, 83% (5/6) of the FOT were sensitive to lymphokine-activated killer (LAK) cells generated by rIL-2. OK-432 and concanavalin A activation of PBL also generated cytotoxic cells, though the cytotoxic activity against FOT was much less than that obtained by LAK cells. The addition of OK-432 to LAK culture medium containing rIL-2 generated effector cells with higher cytotoxicity against FOT than cultures with IL-2 alone. However, the addition of rIFN-alpha 2 in LAK culture medium resulted in the generation of effector cells with lower cytotoxicity. The addition of rIL-2, rIFN-alpha 2, or OK-432 to LAK cells during the in vitro cytotoxicity assay had no significant effect. When FOT target cells were pretreated with OK-432 they became more sensitive to LAK than nontreated tumor cells. However, pretreatment with rIL-2 or rIFN-alpha 2 did not influence cytolysis. These results suggest that the generation of LAK cells in vitro using rIL-2 plus OK-432 may be a more effective way to prepare these cells for adoptive immunotherapy in the treatment of ovarian cancer.