Identification of PE/PPE epitopes of Mycobacterium leprae recognized by peripheral blood mononuclear cells in leprosy (P3332)

Abstract

Abstract Leprosy, a chronic disease caused by the intracellular pathogen Mycobacterium leprae (M leprae), is a major health concern. Mycobacterial PE/PPE proteins may play a role in the interface of host-pathogen interaction and disease development. However, it remains unclear how the immune system recognizes those proteins and their components. Here, we have employed an Internet online-based tool called immune epitope database analysis resource (http://tools.iedb.org) to predict and analyze epitopes of M. leprae PE/PPE proteins. Thirteen candidate T cell epitopes were identified with a potential to bind a broad range of MHC class II haplotypes. Using ELISA, we found that 7/13 of predicted epitopes stimulated IFN-γ production in peripheral blood mononuclear cells (PBMCs) of tuberculoid or reversal reaction leprosy patients but not healthy donors. Among them, ML0588 (7-21) exhibited the broadest stimulatory capacity, eliciting IFN-γ production by PBMCs in 4/7 patients. Taken together, we have utilized the immune epitope database to identify seven peptides encoded by M. leprae PE/PPE proteins as strong candidate T cell epitopes for the induction of IFN-γ production in leprosy patients. These findings suggest that T cell recognition of these proteins may contribute to host defense against leprosy and be of potential use in a diagnostic test for leprosy.