In vitro effect of phagocyte cationic peptides on Coccidioides immitis.

Several cationic peptides that were isolated from rabbit granulocytes exerted fungicidal activity against arthroconidia of Coccidioides immitis in vitro. The fungicidal effect of the cationic peptides required at least 4-8 hr of contact between peptide and fungal cells and appeared to be dependent upon active fungal metabolism. The fungicidal activity was inhibited by increases in the tonicity of the growth medium but was not inhibited by changes in pH. These findings provide a potential mechanism whereby phagocytic cells may limit the spread of infection due to C. immitis.