Phenotyping of circulating CD8+ T cell subsets in human cutaneous leishmaniasis

Abstract: Recovery from CL is usually accompanied with long-lasting protection and induction of strong immune response. The phenotypes, generation and maintenance of central (=TCM) and effector (=TEM) memory T cell subsets in human leishmaniasis are not well known. Profile of T cell subsets were analyzed on peripheral CD8+ T cells from volunteers with history of cutaneous leishmaniasis (HCL). In HCL and control groups, mean frequencies of CCR7+CD45RA+CD8+ naïve and CCR7−CD45RA−CD8+ TEM cells were higher than other subsets before culture, but after stimulation with soluble Leishmania antigen, the frequency of naïve T cells was significantly decreased and the frequency of TEM cells was significantly increased. TEM phenotype composed the highest portion of proliferating Carboxy Fluorescein diacetate Succinimidyl Ester (CFSE)-dim population which was significantly higher in HCL volunteers than in control group. Stimulation of isolated CD8+ memory T cells, but not naïve T cells, from HCL volunteers induced a significantly higher IFN-γ production compared with that of healthy controls. Intracellular IFN-γ staining provided the same result. Memory population is shown to be responsible for Leishmania-induced IFN-γ production. Leishmania-reactive proliferating TEM cells were identified as the most frequent subset which may play a role in recall immune response and protection against Leishmania infection. [Copyright &y& Elsevier]