Signs of an in situ inflammatory reaction in scars of human American tegumentary leishmaniasis.

Skin inflammation plays an important role during the healing of American tegumentary leishmaniasis (ATL), the distribution of cells in active lesions may vary according to disease outcome and parasite antigens in ATL scars have already been shown. We evaluated by immunohistochemistry, 18 patients with 1- or 3-year-old scars and the corresponding active lesions and compared them with healthy skin. Small cell clusters in scars organized as in the active lesions spreaded over the fibrotic tissue were detected, as well as close to vessels and cutaneous glands, despite a reduction in the inflammatory process. Analysis of 1-year-old scar tissue showed reduction of NOS2, E-selectin, Ki67, Bcl-2 and Fas expression. However, similar percentages of lymphocytes and macrophages were detected when compared to active lesions. Only 3-year-old scars showed reduction of CD3(+), CD4(+) and CD8(+)T cells, in addition to reduced expression of NOS2, E-selectin, Ki67 and BCl-2. These results suggest that the pattern of cellularity of the inflammatory reaction observed in active lesions changes slowly even after clinical healing. Analysis of 3-year-old scars showed reduction of the inflammatory reaction as demonstrated by decrease in inflammatory cells and in the expression of cell-activity markers, suggesting that the host-parasite balance was only established after that period.