Lymphocyte subsets, macrophages and Langerhans cells in actinomycetoma and eumycetoma tissue reaction

The aim of this work was to demonstrate, quantify and compare cell elements in the inflammatory infiltrate of 23 skin lesions of actinomycetoma (ACM) and 17 of eumycetoma (EUM). Epidermal Langerhans cells (LC) population was also analyzed in 18 ACM, 13 EUM and ten normal skin samples as control group. Tissue response in both groups of mycetoma showed CD4 and CD8 T lymphocytes surrounding the neutrophils aggregates with macrophages, revealed by CD68 antibody, among them. B lymphocytes were not identified. ACM lesions showed a higher number of CD8+ lymphocytes (P=0.02) and macrophages (P=0.01) when compared with EUM lesions. As well as morphologically altered, displaying irregular and short dendritic processes, LC were depleted both in ACM and EUM lesions (P=0.0004) when compared with normal skin but no difference between both types of mycetoma (P>0.05) was found. Results suggest that cellular mediated immunity may play a role in mycetoma pathogenesis. The morphological alterations and marked reduction of LC in mycetoma lesions might reflect a depressed cellular immune response, partially explaining the chronic course and unresponsiveness to treatment of this group of diseases.