Characterization of an Anticryptococcal Protein Isolated from Human Serum

Human serum at low concentrations inhibits the growth of Cryptococcus neoformans in vitro. Fractionation of serum yielded a purified inhibitory protein with a molecular mass of ∼81.8 kDa, a pI of ∼6.2, and an amino acid sequence that matched that of human transferrin. The inhibitory activity and that of apotransferrin and 5% human serum were reversed by 10 μM freshly prepared FeCl(3).