Response and specificity of antibodies for Candida albicans.

Rabbit antibodies for Candida albicans, reacting in agglutination and fluorescent-antibody reactions, were present in both IgM and IgG protein fractions. The two types of immune globulins were separated from ammonium sulfate-precipitated gamma-globulin either by filtration through a column of Sephadex G-200 or by diethylaminoethyl column chromatography performed by stepwise elution with various concentrations of sodium chloride. In the fluorescent-antibody test, initial separation of the IgG fraction, prior to its conjugation with dye, proved to be essential for the high specificity of this reaction. Investigation of the specificities of the two types of antibodies revealed that the IgG was highly specific, whereas the IgM was not very specific. Each antigen fraction, extracted by various methods, demonstrated its own characteristic antibody response. Only the IgG fraction yielded serotype-specific antibody useful for detection of a serotype of C. albicans in agglutination and fluorescent-antibody tests. The results indicate the importance of IgG for specific serological reactions with the Candida species.