Production and characterization of agglutinating monoclonal antibodies against predominant antigenic factors for Candida albicans.

Two clones, CA4-2 and CA5-4, which produced agglutinating monoclonal immunoglobulin M (IgM) antibodies (MAbs) against mannan antigens of Candida albicans serotype A, were established. The specificity of each MAb was determined by slide agglutination tests for cross-reactivity patterns against the homologous and six other strains of Candida and a strain of Torulopsis: C. albicans serotype B, C. tropicalis, C. guilliermondii, C. krusei, C. parapsilosis, C. pseudotropicalis, and Torulopsis glabrata. The MAb produced by CA4-2 reacted with the homologous, C. tropicalis, and T. glabrata strains, whereas the MAb produced by CA5-4 reacted with the homologous, C. albicans serotype B, and C. tropicalis strains. These results are consistent with results obtained by comparative experiments with several strains of each serotype or species. Specificity of these two MAbs by agglutination was also consistent with the cross-reactivity patterns demonstrated by indirect immunofluorescence staining. The competitive binding experiments by immunofluorescence staining with two MAbs and polyclonal factor sera (PAb factors) 5 and 6 suggested that the MAb from clone CA4-2 did not completely correspond to PAb factor 6 and that the MAb from CA5-4 was distinct from PAb factor 5 in its manner of binding to determinants (the latter was designated 5b), Cross-reactivity patterns, however, furnished evidence that these two MAbs could replace the known PAb factors 6 and 5, respectively, as reagents for aid in the identification of the strains of C. albicans and their serotypes.