Is the in situ inflammatory reaction an important tool to understand the cellular immune response in American tegumentary leishmaniasis?

Abstract

Background: The study of American tegumentary leishmaniasis (ATL) lesions might contribute to the understanding of the dynamics of the infection.

Objectives: To examine the cellular infiltrate of cutaneous ATL lesions and to compare these results with the detection of the parasites and clinical data.

Methods: Lesions of 19 patients with ATL were evaluated through immunohistochemical analysis.

Results: The lesions presented an inflammatory reaction mainly consisting of T cells and macrophages. Analysis of the expression of nitric oxide synthase type 2 (NOS2) showed that its intensity was directly correlated with the number of CD3+ T cells. We also observed an association between high NOS2 expression and low quantity of parasites, highlighting the importance of NOS2 in the elimination of parasites.

Conclusions: The present results suggest that (i) the inflammatory process is intense in cutaneous ATL lesions and maintains a similar activity for several months; (ii) the dynamics of cell infiltration change during this period, with a gradual decrease in CD8+ T cells, probably correlated with a reduction in the parasite number; (iii) neutrophils may participate in the inflammatory process even during later stages of infection; (iv) the relative increase in the number of CD4+ T cells associated with the onset of fibrosis may suggest a participation of these cells in the control of the inflammatory process; and (v) late lesions with tendency for healing usually show focal inflammation. The study of healing lesions might contribute to the understanding of the late steps of the control of the inflammatory process in ATL lesions.