Monoclonal antibody 3H8: a useful tool in the diagnosis of candidiasis

In a previous series of experiments six mAbs were obtained against cell wal l extracts of Candida albicans ATCC 26555. After several studies only one o f them, designated 3H8, has been used to produce a commercial kit for the r apid diagnosis of candidiasis. Bichro-latex albicans (Fomouze Diagnostics). The present study involved the generation and characterization of this mAb as an immunoglobulin G1 which recognizes mannoproteins of high molecular m ass present in the C. albicans cell wall. ELISA assays showed that the pres ence of the epitope recognized by mAb 3H8 was similar in both yeast and myc elial cell walls of C. albicans, in contrast to the epitope for mAb 1B12, w hich is mainly expressed in the yeast cell wall. The 3H8 epitope was locate d at the external surface in C. albicans ATCC 26555, whereas it is partiall y cryptic in the cell wall in other C. albicans strains. No reaction was ob served with other Candida species. Immunohistochemical studies using this a ntibody demonstrated that it specifically recognized C. albicans in tissue, detecting mycelial forms and, to a lesser extent, blastospores. suggesting that it is also a valuable tool in the evaluation of fungal infections in paraffin-embedded tissue, particularly when identification is required.