CALPROTECTIN-MEDIATED ZINC CHELATION AS A BIOSTATIC MECHANISM IN HOST-DEFENSE

The S-100 Ca2+ binding protein, calprotectin, isolated from neutrophil lysates, has been reported to exhibit zinc reversible biostatic activ ity in vitro. We verified these findings with C. albicans and investig ated whether the growth inhibition resulted from zinc deprivation due to chelation by calprotectin. Calprotectin concentrations of 250 mu g/ ml significantly inhibited the growth of C. albicans. This was reverse d by supplementing culture medium with 10 mu M ZnSO4. Incubation of ca lprotectin in culture medium for 24 h prior to inoculation significant ly reduced the minimum inhibitory concentration. When this latter medi um was ultrafiltered to remove the calprotectin and then inoculated wi th C. albicans, significant growth inhibition was still present: again it was reversed by zinc. These findings implicate zinc chelation as a novel, potentially important host defence function of an abundant neu trophil protein.