Antineutrophil cytoplasmic antibodies (ANCA) are suspected of being involved in the pathogenesis of tissue injury in systemic vasculitis. We have investigated the effect of 10 sera from 8 patients with ANCA-associated diseases on the capacity of neutrophils derived from healthy persons to kill ingested Candida albicans. ANCA-containing sera inhibited candidacidal activity by 55-80% in comparison to control sera. This phenomenon could lead to the depression of antimicrobial resistance of patients with ANCA and could be involved in the pathogenesis of granuloma formation.