Flow cytometric analysis of cellular infiltrate from American tegumentary leishmaniasis lesions

Abstract

Variable amounts of gammadelta lymphocytes were present in all lesions, with no association with duration of illness. The highest percentages of interleukin-2R- and interferon-gammaR-positive cells were observed in ML lesions and could render these T cells more susceptible to the effects of these cytokines. The distribution of intralesional T-lymphocyte subsets was quite variable (CD4+ > CD8+ = 18 cases, CD8+ > CD4+ = 12 cases and CD4+ congruent with CD8+ = 4 cases) without any association with clinical parameters, and could explain the controversy regarding proportions of these T-cell subsets in leishmaniasis lesions. Low percentages of Leishmania-reactive CD8+ T cells were observed in blood while an enrichment of CD8+ cells was shown in the inflammatory infiltrate, suggesting that local immunoregulatory factors could favour the recruitment and/or proliferation of local CD8+ lymphocytes. Increased percentages of CD8+ cells observed in older lesions are consistent with the hypothesis that they can mediate healing, although their involvement in tissue damage cannot be ruled out. It is possible that these mechanisms can influence the clinical outcome or even the response to therapy.

The skin homing receptor cutaneous leucocyte-associated antigen (CLA) is up-regulated byLeishmaniaantigens in T lymphocytes during active cutaneous leishmaniasis

“…Several reports have suggested that a huge influx of T cells takes place in lesions [4,7,8], as not only is a higher frequency observed of local lymphocytes responding to L. braziliensis in comparison with blood [9], but also an increased proportion of T CD4 + and T CD8 + cells is reported in older lesions [5,6]. Although the effector T cell response mounted in response to the parasite can lead to a cure, it also seems to be responsible for tissue damage [10,11].…”

“…An incisional biopsy from the skin lesion border was performed for diagnostic purposes, and part of the tissue fragment was separated for cell extraction. Mononuclear cells from leishmaniasis lesions (LeMC) were obtained as described elsewhere [6]. In brief, the skin specimen, stripped of subcutaneous fat, was placed into a tissue sieve, fitted with a 64 mm mesh filter and containing RPMI supplement.…”

“…Molecules involved in the adhesion of Leishmaniainfected macrophages [25] or recruitment of effector lymphocytes to the skin can potentially influence the magnitude of immunopathological process in response to the infection [6,24,26,27]. In situ analyses have shown high levels of LFA1a-and LFA-1b-positive cells in the dermis of leishmaniasis patients, although expressed differentially in CL and diffuse cutaneous leishmaniasis [28].…”

“…+ cells are variable [5,6], suggesting that these T cell subsets can have distinct requirements for their recruitment to lesions.…”

Immunophenotypic characterization of patients with American cutaneous leishmaniasis prior to and after treatment in Pernambuco, Brazil

“…Infections by Leishmania lead to a specific activation of the host immune response (9). Studies indicate the importance of the balance between T CD4 + and CD8 + cells, in which the first ones would have their proportion reduced during the healing process (10,11).…”