Rajiv Kumar Poster 2024

Dr Rajiv Kumar

Banaras Hindu University, India

Persistence of Leishmania-specific T cell Responses in People Cured of Visceral Leishmaniasis 

Poster Abstract

Visceral leishmaniasis (VL), caused by L. donovani, is a visceralizing form of leishmaniasis that exhibits a complex immunological profile. The resolution of the disease is often associated with a Th1 dominant immune response, wherein IFNγ plays a crucial role in parasite clearance. The development and maintenance of immunological memory following infection are essential for resistance to reinfection. However, due to a significant decrease in reported cases, areas with no or low transmission risk losing recurring antigenic exposure, which may lead to the depletion of memory T cells and pose a potential risk of disease resurgence.
 
In this study, we aimed to investigate the specific cytokine responses to soluble leishmanial antigen (SLA) and the presence of reactive T central memory (Tcm) and effector memory (Tem) cells in individuals with a past history of VL from three different settings areas with no transmission (NT; no reported cases in the last five years), areas with continuous transmission (CT; ongoing reported cases), and areas experiencing an outbreak (OB; reappearance of cases after a brief period of absence). Cytometric bead array was employed to measure the production of Th1, Th2, and Th17 cytokines in SLA-stimulated whole blood supernatants. Additionally, flow cytometry was utilized to determine the frequency of Tcm and Tem cells expressing activation and proliferation markers in peripheral blood mononuclear cells (PBMC) treated with SLA. Significant increases in levels of IFNγ, IL-6, IL-2, and the anti-inflammatory cytokine IL-10 were observed in SLA-stimulated whole blood samples from the NT and OB groups.

Furthermore, both CD4+ and CD8+ Tcm and Tem cells exhibited heightened activation. In the OB group, only CD4+ Tcm cells displayed proliferative potential. These findings collectively suggest a mixed cytokine profile resembling the persistence of immune regulatory mechanisms comparable to active disease, and the proliferative response of CD4+ Tcm cells in the OB group may indicate ongoing transmission. 

Biography

Dr. Rajiv Kumar is working as an Assistant Professor at Banaras Hindu University-India.His research interests are to understand the immune mechanisms underlying the progression human Visceral Leishmaniasis, and to distinguish anti-parasitic host immune responses that control disease from the responses that cause disease. Dr. Kumar also works extensively on immuno-biology and immuno-pathogenesis of Post Kala-azar Dermal Leishmaniasis.