Interleukin 10 suppresses phagocytic and antihyphal activities of human neutrophils

We investigated the effects of human interleukin 10 (IL-10) on the antibact erial and antifungal activities of human neutrophils (PMNs) against Staphyl ococcus aureus and Candida albicans, Incubation of PMNs from healthy volunt eers with 20-100 ng/ml of IL-10 at 37 degrees C for 1 h suppressed phagocyt osis of serum-opsonized S. aureus (P=0.02) and blastoconidia of C. albicans (P<0.01). In contrast, 2-100 ng/ml of IL-10 had no effect on superoxide an ion production upon stimulation with phorbol myristate acetate, N-formylmet hionyl leucyl phenylalanine, C. albicans blastoconidia or pseudohyphae; nei ther did it significantly affect conidiocidal or bactericidal activities of PMNs. However, 20-100 ng/ml of IL-10 significantly decreased PMN-induced d amage of C, albicans pseudohyphae (P=0.008). The suppression of phagocytic activity of PMNs against S. am eas and blastoconidia of C, albicans as well as the impairment of PMN-induced hyphal damage may have important implicat ions for understanding the immunosuppressive profile of IL-10 in clinical u sage.