Expression of an epitope by surface glycoproteins of Candida albicans. Variability among species, strains and yeast cells of the genus Candida.

Expression of an antigenic epitope reactive with an IgM monoclonal antibody was studied in 253 Candida isolates by direct agglutination. Isolates of Candida albicans reacted significantly more often with the antibody than did isolates of other species. The agglutination scores for C. albicans isolates from sources associated with possible deep-seated Candida infection were significantly higher than for those from other sources. However, there was considerable overlap of scores between these two groups so that the functional significance of the association is uncertain. There were no associations between agglutination score and C. albicans biotype: multiple isolates from individual patients gave similar agglutination scores. Expression of the epitope within colonies of cloned strains was studied by autoradiography of colony blots on nitrocellulose and by immunoperoxidase staining of colonies in situ. It was found that the epitope was expressed variably by portions of colonies of both agglutination-positive and agglutination-negative strains. Indirect immunofluorescence revealed that expression of the epitope at the surface of C. albicans germ tubes and their associated buds was variable from cell to cell. It was not directly related to morphology or stage of growth of the cells.