ANTIMICROBIAL ACTIVITY OF CALPROTECTIN ISOLATED FROM HUMAN EMPYEMA FLUID SUPERNATANTS

Abscess and empyema fluid supernatants have zinc-reversible antimicrob ial activity that is thought to be due to calprotectin, a calcium- and zinc-binding protein present within neutrophil cytoplasm. The present studies were undertaken to determine if calprotectin isolated from hu man empyema fluid supernatants demonstrated similar antimicrobial acti vity to that of the original specimens. The characteristics of the cal protectin complex on SDS-PAGE and Western blotting with specific antis era were similar in neutrophil lysates and in empyema fluid supernatan ts. Ion-exchange and size-exclusion chromatography were used to obtain highly purified preparations of calprotectin from empyema fluids, and these preparations demonstrated zinc-reversible anti-Candida albicans activity which was similar to that observed in the original specimens . These findings suggest that calprotectin is responsible for most of the growth-inhibitory activity of empyema fluid supernatants against t his organism. (C) 1995 Academic Press, Inc.