Antigen distribution and antigen-presenting cells in skin biopsies of human chromoblastomycosis.

Background:  Chromoblastomycosis is a chronic, suppurative, granulomatous mycosis usually confined to skin and subcutaneous tissues. The host defense mechanisms in chromoblastomycosis have not been extensively investigated. The purpose of the present study was to determine the distribution and pathways of the fungal antigen(s) and the possible role of the different immunocompetent cells in antigen processing in skin lesions. Methods:  The distribution of Fonsecaea pedrosoi antigen(s) in human skin was studied in 18 biopsies from 14 patients with chromoblastomycosis. A purified polyclonal immune serum raised in rabbits against metabolic antigen(s) of F. pedrosoi was used to detect yeast antigen(s) by immunohistochemical procedures. Double immunolabeling was performed with yeast antigen(s) and Langerhans' cells [labeled with anti-S100 protein monoclonal antibody (MoAb)], yeast antigen(s) and factor XIIIa+ dermal dendrocytes (immunolabeled with anti-factor XIIIa polyclonal antibody), and yeast antigen(s) and macrophages (labeled with CD 68 monoclonal antibody). Results:  The F. pedrosoi antigen(s) accumulated in the skin macrophages and, in a few instances, in factor XIIIa+ dendrocytes and Langerhans' cells. Conclusions:  The data obtained suggest that chiefly macrophages, also Langerhans' cells and factor XIIIa+ dermal dendrocytes, function as antigen-presenting cells in chromoblastomycosis.