Immunocytochemical detection of Candida albicans in formalin fixed, paraffin embedded material.

Abstract

AIM: To assess the ability of the commercially available monoclonal antibody 1B12 (BioGenex, San Ramon, USA) to identify C albicans in formalin fixed, paraffin wax embedded material (FFPE). METHODS: Broth cultures of 20 strains of seven Candida species were resuspended in 4% agarose blocks, fixed in formalin for 24 hours, and embedded in paraffin wax. In addition, 16 blocks of FFPE tissue known to contain periodic acid-Schiff positive fungal hyphae were examined. Antigen retrieval involved microwave treatment of specimens in citrate buffer (0.01 M; pH 6.5) before addition of 1B12 antibody for 24 hours. Bound antibody was subsequently detected using a biotinylated link antibody and a peroxidase conjugated streptavidin. RESULTS: Only C albicans strains were 1B12 positive in the agarose blocks. All FFPE tissue blocks were found to contain 1B12 positive hyphal structures, indicating the presence of C albicans. CONCLUSIONS: The ability to identify candida organisms penetrating the lesional tissue in cases of chronic hyperplastic candidosis will help to clarify the role of individual Candida spp in this important form of oral candidosis.