IMMUNOMYCOLOGY - RAPID AND SPECIFIC IMMUNOCYTOCHEMICAL IDENTIFICATIONOF FUNGI IN FORMALIN-FIXED, PARAFFIN-EMBEDDED MATERIAL

We report the rapid (less than 1 hr), immunocytochemical identificatio n of various fungi in formalin-fixed, paraffin-embedded tissues using antisera originally developed for use in immunodiffusion assays. Prima ry antisera directed towards fungal genera including Aspergillus, Blas tomyces, Candida, Coccidioides, Cryptococcus, Histoplasma, and Sporoth rix were examined. The specificity of each antiserum was evaluated by the presence or absence of crossreactivity with other morphologically similar fungi in both paraffin-embedded pure fungal cultures and tissu es with culture-confirmed fungal infections. Each antiserum reacted st rongly with the fungus to which it had been raised, whether examined i n Candida, Cryptococcus, and Sporothrix did not exhibit cross-reactivi ty with any other fungus tested. However, the antisera raised to Asper gillus, Blastomyces, Coccidioides, and Histoplasma demonstrated signif icant crossreactivity with other genera of fungi, thus precluding thei r routine use in diagnostic immunocytochemistry. The results indicate that immunocytochemistry may provide an important adjunct to other met hods, such as immunodiffusion or complement fixation assays and histoc hemical stains such as the Grocott methenamine silver or periodic acid -Schiff, when attempts are made to specifically identify certain fungi in formalin-fixed, paraffin-embedded tissues before mycology culture results are available.