A simplified in vitro assay of delayed hypersensitivity in diagnosis of dermatomycoses.

A tissue culture technique for detection of cellular hypersensitivity in an animal model of dermatomycoses is presented. It is based on specific inhibition of migration of leukocytes sensitized to dermatophytic antigens. The application and specificity of this new immunological technique were studied in guinea pigs infected with Trichophyton rubrum, Microsporum vanbreuseghemii, and Epidermophyton floccosum. In all the infected animals, sensitivity to trichophytin was demonstrated to be independent of the clinical disease phase. The in vivo skin-test reactions were common to those of the group of dermatophytes and did not distinguish between the different species. A statistical difference was observed in the leukocyte migration indices of sensitized cells to the homologous and the heterologous antigens of these pathogens (p less than 0.05, Student's test). It is concluded that the leukocyte migration inhibition assay provides a specific expression of cellular hypersensitivity and may be considered suitable for investigation of cellular immunity in vitro in clinical diagnosis or research. This is a simple, rapid, and inexpensive technique that requires small volumes of peripheral blood.