Immunization with f-Met peptides induces immune reactivity against Mycobacterium tuberculosis

Objective: To determine whether synthetic peptides containing an amino terminal formyl-methionine residue and corresponding to the sequence of several proteins produced by Mycobacterium tuberculosis, would elicit an immune response in mice.

Design: Peptides corresponding to the amino termini of 8 M. tuberculosis proteins and initiating with formyl methionine residues were synthesized. The ability of these peptides to bind to the mouse non-classical MHC class I molecule H-2M3^awas determined by flow microfluorimetry. These peptides were used to pulse dendritic cells that were then injected into normal mice. These mice were subsequently challenged with aerosolized M. tuberculosis and, 30 days later, the number of viable bacteria in the lungs was determined.

Results: Four of the 8 synthetic peptides bound to H-2M3^aand stabilized its expression on the cell surface. Injection of mice with dendritic cells pulsed with H-2M3^abinding peptides elicited non-MHC restricted cytotoxic T lymphocytes that killed peptide pulsed target cells and macrophages infected with M. tuberculosis. Immunization of mice with syngeneic dendritic cells pulsed in vitro with 2 of these peptides led to retardation of the growth of M. tuberculosis following aerosol challenge.

Conclusion: Peptides that bind to non-polymorphic class I molecules can elicit immune reactivity directed towards M. tuberculosis.