Characterization of a Mycobacterium tuberculosis Peptide That Is Recognized by Human CD4+ and CD8+ T Cells in the Context of Multiple HLA Alleles

Abstract

The secreted Mycobacterium tuberculosis 10-kDa culture filtrate protein (CFP)10 is a potent T cell Ag that is recognized by a high percentage of persons infected with M. tuberculosis. We determined the molecular basis for this widespread recognition by identifying and characterizing a 15-mer peptide, CFP1071–85, that elicited IFN-γ production and CTL activity by both CD4+ and CD8+ T cells from persons expressing multiple MHC class II and class I molecules, respectively. CFP1071–85 contained at least two epitopes, one of 10 aa (peptide T1) and another of 9 aa (peptide T6). T1 was recognized by CD4+ cells in the context of DRB1*04, DR5*0101, and DQB1*03, and by CD8+ cells of A2+ donors. T6 elicited responses by CD4+ cells in the context of DRB1*04 and DQB1*03, and by CD8+ cells of B35+ donors. Deleting a single amino acid from the amino or carboxy terminus of either peptide markedly reduced IFN-γ production, suggesting that they are minimal epitopes for both CD4+ and CD8+ cells. As far as we are aware, these are the shortest microbial peptides that have been found to elicit responses by both T cell subpopulations. The capacity of CFP1071–85 to stimulate IFN-γ production and CTL activity by CD4+ and CD8+ cells from persons expressing a spectrum of MHC molecules suggests that this peptide is an excellent candidate for inclusion in a subunit antituberculosis vaccine.

Mycobacterium tuberculosis-Specific CD8+ T Cells and Their Role in Immunity

“…DNA vaccination of mice elicited CTL activity against four of the peptides. Two of the peptides (Ag85B [143][144][145][146][147][148][149][150][151][152] and Ag85B [199][200][201][202][203][204][205][206][207] ) were able to stimulate short-term antigenspecific CD8 + T cell lines from BCG-vaccinated individuals. In the case of Ag85B [199][200][201][202][203][204][205][206][207] , tetramers were made and CD8 + T cells that stained with the tetramers were enriched in the short-term cell lines.…”

“…Finally, CFP10-specific CD8 + T cells were detected at frequencies as high as 1/700 total CD8 + T cells, suggesting that CFP10 can be an immunodominant antigen in people. A follow-up study by Shams et al defined a 15mer peptide (CFP10 [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85], which contains at least two distinct epitopes, each one that can be presented by class I and II MHC to both CD8 + and CD4 + T cells, respectively (147). The promiscuity of these epitopes for different alleles of class I and class II MHC proteins may explain why nearly 100% of people with latent M. tuberculosis infection recognize CFP10.…”

Enzyme-linked Immunospot and Tuberculin Skin Testing to Detect Latent Tuberculosis Infection

“…The assay was performed as previously described (see Methods in the online supplement) (11,12,19). The mean number of spots in duplicate negative control wells was six or less in 406 of 413 cases.…”

MHC class II Tetramer Guided Detection of Mycobacterium tuberculosis‐specific CD4+ T Cells in Peripheral Blood from Patients with Pulmonary Tuberculosis

“…Antigenspecific immune reactivity directed against these antigens has been described with certain advantages. For instance, individual CFP10 peptides may be presented by multiple MHC alleles [2] and ESAT-6-directed immune responses are elevated in tuberculous pleural effusions when compared with the peripheral circulation [3]. More recently, tetramer-based read-out systems have been developed to objectively enumerate and visualize antigen-specific CD4 + T cells in blood [4].…”