To Study the Alteration in Thymic Functionality in Experimental Visceral Leishmaniasis

Abstract

Visceral Leishmaniasis (VL) is a neglected tropical disease and is potentially-fatal. Species belonging to L.donovani complex are the causative agent of VL in humans. Host immunity against VL critically depends on T cell based cell mediated immune response. VL is associated with lymphopenia such that progression of VL involves depletion of T cells. However, the origin and mechanism of T cell alterations in peripheral blood is not clearly understood. So we have tried to understand the origin of T cell changes in context of thymic functions which is the site of T cell development based on T cell Receptor Excision Circles analysis in experimental murine VL model. The result shows higher copy number of T cell Receptor Excision Circles (TRECs) in peripheral blood and a trend towards increase in developing thymocytes from thymi of infected mice compared to control uninfected group. The results imply that the peripheral T cell repertoires comprise a significant fraction of unexpanded naïve T cells. TREC change in thymocytes is statistically not significant implying no change in thymic output of naïve T cells. Thus our findings show that leishmania parasite can modulate T cell arm of immunity by altering the proliferation capacity of recent thymic naïve T cell emigrants.