title: ML1419c peptide immunization induces Mycobacterium leprae-specific HLA-A*0201-restricted CTL in vivo with potential to kill live mycobacteria.
abstract: MHC class I-restricted CD8(+) T cells play an important role in protective immunity against mycobacteria. Previously, we showed that p113-121, derived from Mycobacterium leprae protein ML1419c, induced significant IFN-γ production by CD8(+) T cells in 90% of paucibacillary leprosy patients and in 80% of multibacillary patients' contacts, demonstrating induction of M. leprae-specific CD8(+) T cell immunity. In this work, we studied the in vivo role and functional profile of ML1419c p113-121-induced T cells in HLA-A*0201 transgenic mice. Immunization with 9mer or 30mer covering the p113-121 sequence combined with TLR9 agonist CpG induced HLA-A*0201-restricted, M. leprae-specific CD8(+) T cells as visualized by p113-121/HLA-A*0201 tetramers. Most CD8(+) T cells produced IFN-γ, but distinct IFN-γ(+)/TNF-α(+) populations were detected simultaneously with significant secretion of CXCL10/IFN-γ-induced protein 10, CXCL9/MIG, and VEGF. Strikingly, peptide immunization also induced high ML1419c-specific IgG levels, strongly suggesting that peptide-specific CD8(+) T cells provide help to B cells in vivo, as CD4(+) T cells were undetectable. An additional important characteristic of p113-121-specific CD8(+) T cells was their capacity for in vivo killing of p113-121-labeled, HLA-A*0201(+) splenocytes. The cytotoxic function of p113-121/HLA-A*0201-specific CD8(+) T cells extended into direct killing of splenocytes infected with live Mycobacterium smegmatis expressing ML1419c: both 9mer and 30mer induced CD8(+) T cells that reduced the number of ML1419c-expressing mycobacteria by 95%, whereas no reduction occurred using wild-type M. smegmatis. These data, combined with previous observations in Brazilian cohorts, show that ML1419c p113-121 induces potent CD8(+) T cells that provide protective immunity against M. leprae and B cell help for induction of specific IgG, suggesting its potential use in diagnostics and as a subunit (vaccine) for M. leprae infection.
authors.affiliation: Department of Infectious Diseases, Leiden University Medical Center, Leiden 2333 ZA, The Netherlands. ageluk@lumc.nl
authors.forename: Annemieke
authors.initials: A
authors.lastname: Geluk
authors.forename: Susan J F
authors.initials: SJ
authors.lastname: van den Eeden
authors.forename: Karin
authors.initials: K
authors.lastname: Dijkman
authors.forename: Louis
authors.initials: L
authors.lastname: Wilson
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Kees L M C
authors.initials: KL
authors.lastname: Franken
authors.forename: John S
authors.initials: JS
authors.lastname: Spencer
authors.forename: Maria C V
authors.initials: MC
authors.lastname: Pessolani
authors.forename: Geraldo M B
authors.initials: GM
authors.lastname: Pereira
authors.forename: Tom H M
authors.initials: TH
authors.lastname: Ottenhoff
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology*; D015234:HLA-A Antigens / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D015789:HLA-A2 Antigen; D006801:Humans; D007918:Leprosy / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009166:Mycobacterium leprae / Q000276:immunology* / Q000472:pathogenicity; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; C561891:ML1419c protein (113-121), Mycobacterium leprae; D010446:Peptide Fragments; D022223:Vaccines, Subunit