RECALLING IMMUNE RESPONSES POST VISCERAL LEISHMANIASIS

Abstract

Intro: Although visceral leishmaniasis (VL) is in the peri-elimination phase with very low to no transmission rates, the risk of future outbreaks can never be ignored. Memory is the fundamental feature of the immunity that confers long- term protection against the pathogens. Local cellular factors in cellular microenvironment remains crucial for generation and maintenance of memory responses. Overall, there is little information on the memory immune responses, thus, we aimed to assess the longevity and sustenance of the immune responses in past VL cases. Methods: The study was performed on whole blood and PBMCs from past VL cases from different time points (six months, one year, two, three, five and ten years) after treatment. Antigen specific immune responses were compared between the whole blood and the PBMCs after ex vivo stimulation. PBMCs were also stimulated with exogenous cytokines for measuring the degree of immune responses and alterations in the memory cells profile . Serum/plasma were collected from past cases and used for direct agglutination assay (DAT), ELISA and cytometric bead assay (CBA) analysis. Findings: We found significantly high levels of anti- leishmanial antibodies in subjects from different time points after treatment. Whole blood as well as PBMCs from different post-treated groups exhibited Leishmania specific immune responses. Intriguingly, providing the clues regarding the limiting factor for the development of long-term immune responses. Discussion: We provided evidences regarding the alterations in the antigen specific immunological profiles from different post-treated subjects. Exogenous cytokine-based modulation of T-cells responses indicated for potential candidates for boosting the pre-existing memory during disease outbreaks. Conclusion: In conclusion, the findings presented in the study demonstrated that immune responses can readily induced has implications for understanding the longevity of the immune responses and immune boosting strategy for enhancing the memory responses that eventually will serve to determine the infection outcomes in endemic population.