Detection of keratinolytic proteinase in skin tissues from guinea pigs infected with Microsporum canis by an immunoperoxidase technique

An immunoperoxidase technique was performed to detect keratinolytic proteinase (KPase) in sections of the skin taken from guinea pigs infected with Microsporum canis and in cultured M. canis using polyclonal antisera to purified KPase. Of tissue samples from guinea pigs infected with M. canis, all sections of erythematous lesions showed positive staining mainly in the horny layer and the hair follicles. Positive depositions were seen only at the level of the outer and inner root sheaths of the hair follicles in sections of skin lesions showing scales and crusts. However, sections from areas of alopecia following desquamation of the crust showed no depositions of bright red reaction products. The patterns of deposition of KPase according to the clinical course of experimental dermatophytosis were consistent with the existence of organisms observed by PAS and methenamine silver stains. These results suggest that KPase may be produced during infection with M. canis after the development of erythema and before desquamation of the crust.