Comparison of the metal-binding anticandidal activities of serum and abscess fluid supernatants

Abstract

Serum transferrin appears to play a role in host defense by competing with invading microorganisms for iron. The purpose of the present study was to compare this activity to a similar one recently described in abscess fluids and based on a calcium- and zinc-binding protein called calprotectin. Serum and abscess fluid supernatants were collected and pooled from groups of five to 10 C57BL/6 mice with experimental Candida albicans abscesses; serum was also collected from normal animals. In four experiments, serum was found to reduce in vitro C. albicans growth in Sabouraud glucose broth by a mean of 97.9% at 10 mg ml-1 of protein; this effect was reversed by adding 3-10 microM FeCl3, but not by similar amounts of ZnSO4. Abscess fluid supernatants had a greater effect, reducing growth by 99.9% at 1 mg ml-1 and 76.1% at 0.1 mg ml-1 of total protein; this effect was reversed by 3-10 microM ZnSO4, but not FeCl3. Although abscess fluid supernatants were effective when high inocula (10,000 yeast cells) were used, serum from the infected mice inhibited growth only with lower inocula (10-100 yeast cells). In a separate study, serum from infected mice (eight pools) reduced growth (by a range of 36 to 97%), whereas serum from normal mice (five pools) actually enhanced growth in this system (by a range of 173 to 595%).(ABSTRACT TRUNCATED AT 250 WORDS)