DIFFERENT SENSITIVITY TO INTERLEUKIN-4 OF INTERLEUKIN-2 AND INTERFERON ALPHA-INDUCED CD69 ANTIGEN EXPRESSION IN HUMAN RESTING NK CELLS AND CD3+, CD4-, CD8- LYMPHOCYTES

The effect of rIL-4 on CD69 antigen expression induced by rIL-2 or by rINF-α on human resting NK cells and CD3+, CD4-, CD8- T lymphocytes has been investigated. rIL-4 drastically inhibited CD69 antigen expression induced by rIL-2 in both cell types. In contrast, rIL-4 did not alter rINF-α-induced CD69 antigen expression. Consistent results were obtained evaluating the cytolytic activity of NK cells against the Raji target cell line: rINF-α-induced lytic activity was not inhibited by rIL-4, while rIL-2-induced lytic activity was drastically inhibited. Proliferative activity of NK cells induced by rIL-2, in contrast, was only slightly reduced by rIL-4. rIL-4 did not alter the expression of the β chain of IL-2 receptor, evaluated in NK cells by indirect immunofluorescence. Expression of the α chain of IL-2 receptor could not be detected in NK cells by indirect immunofluorescence. It can therefore be suggested that the selective inhibitory effect of rIL-4 on rIL-2-induced activation of NK cells is not mediated by downregulation of α and β chains of IL-2 receptor. © 1992.