Delayed-type hypersensitivity response to crude and fractionated antigens from Fonsecaea pedrosoi CMMI 1 grown in different culture media.

Chromoblastomycosis is a subcutaneous fungal disease caused by dematiaceous fungi, especially by Fonsecaea pedrosoi, regarded as its major causative agent in Brazil. In recent years there has been a decline in the use of skin testing for delayed-type hypersensitivity (DTH) in epidemiological surveys of fungal infections, mainly because of the unpredictability of positive reactions and lack of specificity of the antigens used. The aim of the present study was to assess delayed-type skin tests in guinea pigs experimentally infected with F. pedrosoi using exoantigens prepared from two culture filtrates. Sixteen adult male guinea pigs were inoculated intratesticularly with fungal cells and submitted to sensitivity assays 4 weeks after inoculation. They received an intradermal injection with crude and fractionated antigens from Alviano's and Smith's cultures, and were assessed 24 and 48 h thereafter. Except for one animal, all of them had positive indurations after 48 h. There were no statistical differences between the measurements at 24 and 48 h for each exoantigen used, neither among the induration measurements at 48 h when different preparations were compared. Our results suggest that a delayed-type skin test using antigens produced in synthetic media may be useful for the assessment of primary exposure to chromoblastomycosis.