IDENTIFICATION OF A MYCOBACTERIUM LEPRAE-SPECIFIC T-CELL EPITOPE ON THE 70 KDA HEAT-SHOCK PROTEIN

A major antigen of the leprosy bacillus, Mycobacterium leprae, is the 70 kDa heat shock protein (Hsp70), which has significant sequence homo logy with Hsp70 from other mycobacterial species as well as Hsp70 from eukaryotes. A unique region of 70 amino acids at the C-terminus of th e M, leprae Hsp70 has been previously identified. This study investiga ted whether mice immunized with the C-terminal fragment of M. leprae H sp70 recognize T cell epitopes in this species-specific portion of the molecule. Murine lymphoproliferative responses to overlapping peptide s 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 sequ ence 567-591. Lymph node cells from mice immunized with this peptide r ecognized both the C-terminal fragment and the whole Hsp70 molecule. M oreover, mice immunized with the same peptide responded to the whole H sp70 molecule in a delayed-type hypersensitivity reaction. The signifi cance of M. leprae-specific T cell epitopes in the host response to my cobacterial infection is discussed.