title: Mycobacterium tuberculosis-reactive CD8+ T lymphocytes: the relative contribution of classical versus nonclassical HLA restriction.
abstract: Previous studies in mice and humans models have suggested an important role for CD8+ T cells in host defense to Mycobacterium tuberculosis (Mtb). In humans, CD8+ Mtb-reactive T cells have been described that are HLA-A2-, B52-, as well as CD1-restricted. Recently, we have described Mtb-specific CD8+ T cells that are neither HLA-A-, B-, or C- nor group 1 CD1-restricted. At present, little is known about the relative contribution of each of these restriction specificities to the overall CD8+ response to Mtb. An IFN-gamma enzyme-linked immunospot assay was used to determine the frequency of Mtb-reactive CD8+ T cells directly from PBMC. The effector cell frequency among five healthy purified protein derivative-positive subjects was 1/7,600 +/- 4,300 compared with 1/16,000 +/- 7,000 in six purified protein derivative-negative controls. To determine the frequencies of classically, CD1-, and nonclassically restricted cells, a limiting dilution analysis was performed. In one purified protein derivative-positive subject, 192 clones were generated using Mtb-infected dendritic cells (DC). Clones were assessed for reactivity against control autologous DC, Mtb-infected autologous DC, and HLA-mismatched CD1+ targets (DC), as well as HLA-mismatched CD1- targets (macrophages). Of the 96 Mtb-reactive CD8+ T cell clones, four (4%) were classically restricted and 92 (96%) were nonclassically restricted. CD1-restricted cells were not detected. Of the classically restricted cells, two were HLA-B44 restricted and one was HLA-B14 restricted. These results suggest that while classically restricted CD8+ lymphocytes can be detected, they comprise a relatively small component of the overall CD8+ T cell response to Mtb. Further definition of the nonclassical response may aid development of an effective vaccine against tuberculosis.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Oregon Health Sciences, University/Portland Veterans Affairs Medical Center, Portland, OR 97201, USA. lewinsod@OHSU.edu
authors.forename: D M
authors.initials: DM
authors.lastname: Lewinsohn
authors.forename: A L
authors.initials: AL
authors.lastname: Briden
authors.forename: S G
authors.initials: SG
authors.lastname: Reed
authors.forename: K H
authors.initials: KH
authors.lastname: Grabstein
authors.forename: M R
authors.initials: MR
authors.lastname: Alderson
mesh_terms: D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D018949:Antigens, CD1 / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D002999:Clone Cells; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008213:Lymphocyte Activation / Q000276:immunology; D018655:Lymphocyte Count; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D014373:Tuberculin / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology
chemical_list: D018949:Antigens, CD1; D006680:HLA Antigens; D014373:Tuberculin