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The potential involvement of apoptosis in the pathogenesis of visceral leishmaniasis (VL) was examined by studying spontaneous andLeishmaniaantigen (LAg)-induced apoptosis using cryopreserved peripheral blood mononuclear cells (PBMC) of Sicilian patients with VL. Results indicate that monocytes and T lymphocytes from acute VL patients show a significantly higher level of apoptosis compared with that observed in healed subjects. The percentage of apoptotic cells was higher in monocytes than in T lymphocytes. T cells involved in programmed cell death (PCD) were mainly of the CD4+ phenotype. In particular, the T helper 1-type (Th1) subset, as evaluated by chemokine receptor-5 (CCR5) expression, is involved in this process. Cell death in Th1-type uses a CD95-mediated mechanism. Furthermore, Th1-type CCR5+ cells are prone to cell suicide in an autocrine or paracrine way, as attested by enhanced expression of CD95L in acute VL patients. The reduction in Th1-type cells by apoptosis was confirmed by the decrease in interferon-γ secretion. In conclusion, apoptosis of monocytes, CD4+ and CD4+ CCR5+ T cells could be involved in the failure of cell mediated immunity that is responsible for severe immune-depression in VL. [ABSTRACT FROM AUTHOR]

γδ T lymphocytes are considered to represent a link between the inflammatory response and adaptive immunity. In the present paper we investigated whether these cells play any role in the remodeling of the immune system described in the elderly. We show that the absolute number of γδ T cells in peripheral blood of old and very old subjects is reduced. Moreover, γδ T cells from old people and centenarians show enhanced levels of the early activation marker CD69 both after culture in medium alone and in LPS-stimulated cells. Furthermore, they show a basal increased production of tumor necrosis factor (TNF)-α as evaluated at the single cell level. Additionally, the response of these cells to IPP in ‘in vitro’ cultures is in part impaired. These results suggest that the high level of basal activation of γδ T cells is due to the ‘inflamed’ environment. However, the changes in number and function of γδ T lymphocytes might influence the resolution of inflammatory immune responses in the elderly. [Copyright &y& Elsevier]