Scheynius A, Faergemann J, Forsum U, Sjöberg O.
DOI: 10.2340/0001555564473479

The cellular response in pityriasis (tinea) versicolor lesions was analysed in situ with an immunohistochemical double staining technique combined with periodic acid-Schiff staining in frozen sections of skin biopsies from 9 patients. The proportions of B and T cells and subpopulations of T cells in the blood were normal as were the proliferative responses of blood mononuclear cells against various B- and T-cell mitogens and antigens. Fungi were observed in stratum corneum in all lesions, and there were moderate cell infiltrates in both epidermis and dermis as compared to biopsies from normal-looking skin. The majority of the infiltrating perivascular cells reacted with anti-Leu 1 antibodies (all mature peripheral T cells). Anti-Leu 2a reactive cells (´suppressor/cytotoxic´ phenotype) were few and scattered, whereas anti-Leu 3a reactive cells (´helper/inducer´ phenotype) dominated. This investigation demonstrates that pityriasis versicolor is not a simple overgrowth of the fungus in stratum corneum, but is accompanied by infiltrating immunocompetent cells in both epidermis and dermis.