title: Identification of MHC class II restricted T-cell-mediated reactivity against MHC class I binding Mycobacterium tuberculosis peptides.
abstract: Major histocompatibility complex (MHC) class I restricted cytotoxic T lymphocytes (CTL) are known to play an important role in the control of Mycobacterium tuberculosis infection so identification of CTL epitopes from M. tuberculosis is of importance for the development of effective peptide-based vaccines. In the present work, bioinformatics technology was employed to predict binding motifs of 9mer peptides derived from M. tuberculosis for the 12 HLA-I supertypes. Subsequently, the predicted peptides were synthesized and assayed for binding to HLA-I molecules in a biochemically based system. The antigenicity of a total of 157 peptides with measured affinity for HLA-I molecules of K(D) ≤ 500 nM were evaluated using peripheral blood T cells from strongly purified protein derivative reactive healthy donors. Of the 157 peptides, eight peptides (5%) were found to induce T-cell responses. As judged from blocking with HLA class I and II subtype antibodies in the ELISPOT assay culture, none of the eight antigenic peptides induced HLA class I restricted CD8(+) T-cell responses. Instead all responses were blocked by pan-HLA class II and anti-HLA-DR antibodies. In addition, CD4(+) T-cell depletion before the 10 days of expansion, resulted in total loss of reactivity in the ELISPOT culture for most peptide specificities. FACS analyses with intracellular interferon-γ staining of T cells expanded in the presence of M. tuberculosis peptides confirmed that the responsive cells were indeed CD4(+). In conclusion, T-cell immunity against HLA-I binding 9mer M. tuberculosis-derived peptides might in many cases turn out to be mediated by CD4(+) T cells and restricted by HLA-II molecules. The use of 9mer peptides recognized by both CD8(+) and CD4(+) T cells might be of importance for the development of future M. tuberculosis peptide-based vaccines.
authors.affiliation: Department of International Health, Immunology and Microbiology, Faculty of Heath Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Wang
authors.forename: Sheila T
authors.initials: ST
authors.lastname: Tang
authors.forename: Anette
authors.initials: A
authors.lastname: Stryhn
authors.forename: Sune
authors.initials: S
authors.lastname: Justesen
authors.forename: Mette V
authors.initials: MV
authors.lastname: Larsen
authors.forename: Morten H
authors.initials: MH
authors.lastname: Dziegiel
authors.forename: David M
authors.initials: DM
authors.lastname: Lewinsohn
authors.forename: Søren
authors.initials: S
authors.lastname: Buus
authors.forename: Ole
authors.initials: O
authors.lastname: Lund
authors.forename: Mogens H
authors.initials: MH
authors.lastname: Claesson
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006682:HLA-DP Antigens / Q000276:immunology / Q000378:metabolism; D006684:HLA-DR Antigens / Q000276:immunology / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000276:immunology* / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D010455:Peptides / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D018984:Epitopes, T-Lymphocyte; D006682:HLA-DP Antigens; D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D007371:Interferon-gamma