Corticosteroids inhibit the generation of lymphokine-activated killer activity in vitro.

In phase-I clinical trials of adoptive immunotherapy using lymphokine-activated killer (LAK) cells plus recombinant interleukin-2 (rIL-2) (Cetus) for the treatment of malignant glioma, we observed that blood mononuclear cells (MNC) from patients dependent on dexamethasone for management of cerebral edema produced substantially less LAK activity as compared to MNC of normal blood donors or glioma patients not receiving steroid therapy. Therefore, we examined the in vitro effects, brought about by therapeutically attainable concentrations of various corticosteroids, on the proliferative response, production of gamma interferon (IFN-gamma), and induction of LAK activity from blood MNC of normal donors. Incubation in media containing rIL-2 (1000 U/ml) with either dexamethasone, hydrocortisone, methylprednisolone, or prednisolone profoundly affected all of these parameters. First, while 0.01 micrograms/ml of either dexamethasone or hydrocortisone caused a slight enhancement of the mitogenic response of lymphocytes to phytohemagglutinin, a dose-dependent decline occurred as concentrations increased to 10 micrograms/ml. The addition of prednisolone and methylprednisolone elicited a dose-dependent inhibition of lymphocyte proliferation over the entire concentration range tested. At 0.1 microgram/ml or higher, dexamethasone, hydrocortisone, methylprednisolone and prednisolone significantly (P less than 0.02) inhibited the production of IFN-gamma: respectively 18.9%, 4.4%, 2.2%, and 12.3% of the IFN-gamma produced by MNC in the absence of steroids. All four corticosteroids inhibited the induction of LAK activity. Compared to MNC that had been incubated with 1000 U/ml rIL-2 alone, MNC cultured with rIL-2 and 10 micrograms/ml either dexamethasone or prednisolone demonstrated significantly lower cytotoxicity (P less than 0.05) for the natural-killer-cell-resistant cell line, Daudi. Culturing MNC with hydrocortisone had a more dramatic result, causing a significant decline (P less than 0.01) in lytic activity at both 1.0 micrograms/ml and 10 micrograms/ml, while incubation with methylprednisolone produced a significant drop (P less than 0.02) in LAK-mediated cytotoxicity at 0.1 micrograms/ml as well as 1.0 micrograms/ml and 10 micrograms/ml. When cytotoxicity was expressed as lytic units per million effectors, a dose-response decline in lytic activity was once again apparent, with hydrocortisone, methylprednisolone and prednisolone showing significant inhibition (P less than 0.05) at both 1.0 micrograms/ml and 10 micrograms/ml and dexamethasone at 10 micrograms/ml (P less than 0.01). These results indicate that corticosteroids commonly used in the management of cere