The relative resistance of lymphokine activated killer cells to suppression by prostaglandins and glucocorticoids

The possibility that lymphokine-activated killer (LAK) cells versus spontaneous natural killer (NK) cells show relative resistance to the suppressive effects of the immunoregulatory molecules prostaglandin E₂ (PGE₂) and dexamethasone (DMO) was investigated. LAK cells were produced $\text{in vitro}$ by the incubation of human peripheral mononuclear cells (PBMC) for three days in the presence of interleukin-2 (IL-2). Cytotoxicity of NK and LAK cells were measured by conventional 4 hour Cr⁵¹ release assays using K562 and Daudi target cells. LAK cells were relatively resistant to suppression by PGE₂. For example, NK cytotoxicity was significantly suppressed by 10⁻⁶ M PGE₂. In contrast, LAK cells required a 30 to 100 higher concentration of PGE₂ according to the target used to achieve similar suppression. Likewise, a differential resistance to DMO was seen. NK cells were significantly suppressed by 10-³M DMO while a 1000 fold higher concentration was needed for similar suppression of LAK cytotoxicity. Overall, the results show that LAK cells are relatively resistant to immunoregulatory suppressive factors.