Identification of a Mycobacterium leprae ‐specific T cell epitope on the 70 kDa heat shock protein

Summary A major antigen of the leprosy bacillus, Mycobacterium leprae , is the 70 kDa heat shock protein (Hsp70), which has significant sequence homology with Hsp70 from other Mycobacterial species as well as Hsp70 from eukaryotes. A unique region of 70 amino acids at the C ‐terminus of the M. leprae Hsp70 has been previously identified. This study investigated whether mice immunized with the C ‐terminal fragment of M. leprae Hsp70 recognize T cell epitopes in this species‐specific portion of the molecule. Murine lymphoproliferative responses to overlapping peptides spanning the C ‐terminal 70 amino acids were restricted to mice of an H‐2 b haplotype and identified the presence of a determinant in sequence 567–591. Lymph node cells from mice immunized with this peptide recognized both the C ‐terminal fragment and the whole Hsp70 molecule. Moreover, mice immunized with the same peptide responded to the whole Hsp70 molecule in a delayed‐type hypersensitivity reaction. The significance of M. leprae ‐specific T cell epitopes in the host response to Mycobacterial infection is discussed.