INTERLEUKIN (IL)-15 ENHANCES ANTIBODY-DEPENDENT CELLULAR CYTOTOXICITYAND NATURAL-KILLER ACTIVITY IN NEONATAL CELLS

Interleukin (IL)-15 is a novel cytokine that is very similar to IL-2 i n receptor specificity and biological activities. We compared the abil ity of IL-15 and IL-12 to enhance the cytotoxicity of neonatal (cord b lood) and adult mononuclear cells (MNC) in both natural killer (NK) an d antibody-dependent cellular cytotoxicity (ADCC) assays. Incubation w ith IL-15 (10 ng/ml) or IL-12 (1 ng/ml) for 18 h enhanced the NK activ ity (using K562 target cells) of both cord and adult MNC, increasing c ord cell cytotoxicity threefold. Similar enhancement was seen in ADCC assays using erythrocyte targets and NK-resistant CEM cells coated wit h HIV gp-120 antigen. Incubation of cord cells with IL-15 or IL-12 for 1 week increased both NK and ADCC, although the combination produced less of an effect than either cytokine alone. IL-15 also increased the percentage of CD16(+)/CD56(+) cells after 1 week incubation. This enh ancement of NK and ADCC activities and the number of NK cells by IL-15 suggests it may be clinically useful in treating immunodeficient pati ents. (C) 1998 Academic Press.