Lysozyme: primary bactericidin in human plasma serum active against Bacillus subtilis.

The in vitro bactericidal reaction of human plasma serum against Bacillus subtilis was investigated. Human lysozyme was purified to homogeneity, and antiserum was prepared against the enzyme. The anti-lysozyme immunoglobulin G was used as a specific inhibitor in bactericidal and bacteriolytic reactions. It was found that at low serum concentrations lysozyme was the primary bactericide active against B. subtilis. At appreciably higher serum concentrations, a lysozyme-independent bactericidal activity was also demonstrated.