title: CD1c tetramers detect ex vivo T cell responses to processed phosphomycoketide antigens.
abstract: CD1c is expressed with high density on human dendritic cells (DCs) and B cells, yet its antigen presentation functions are the least well understood among CD1 family members. Using a CD1c-reactive T cell line (DN6) to complete an organism-wide survey of M. tuberculosis lipids, we identified C32 phosphomycoketide (PM) as a previously unknown molecule and a CD1c-presented antigen. CD1c binding and presentation of mycoketide antigens absolutely required the unusual, mycobacteria-specific lipid branching patterns introduced by polyketide synthase 12 (pks12). Unexpectedly, one TCR responded to diversely glycosylated and unglycosylated forms of mycoketide when presented by DCs and B cells. Yet cell-free systems showed that recognition was mediated only by the deglycosylated phosphoantigen. These studies identify antigen processing of a natural bacterial antigen in the human CD1c system, indicating that cells act on glycolipids to generate a highly simplified neoepitope composed of a sugar-free phosphate anion. Using knowledge of this processed antigen, we generated human CD1c tetramers, and demonstrate that CD1c-PM complexes stain T cell receptors (TCRs), providing direct evidence for a ternary interaction among CD1c-lipid-TCR. Furthermore, PM-loaded CD1c tetramers detect fresh human T cells from peripheral blood, demonstrating a polyclonal response to PM antigens in humans ex vivo.
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: Dalam
authors.initials: D
authors.lastname: Ly
authors.forename: Anne G
authors.initials: AG
authors.lastname: Kasmar
authors.forename: Tan-Yun
authors.initials: TY
authors.lastname: Cheng
authors.forename: Annemieke
authors.initials: A
authors.lastname: de Jong
authors.forename: Shouxiong
authors.initials: S
authors.lastname: Huang
authors.forename: Sobhan
authors.initials: S
authors.lastname: Roy
authors.forename: Apoorva
authors.initials: A
authors.lastname: Bhatt
authors.forename: Ruben P
authors.initials: RP
authors.lastname: van Summeren
authors.forename: John D
authors.initials: JD
authors.lastname: Altman
authors.forename: William R
authors.initials: WR
authors.lastname: Jacobs
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Adams
authors.forename: Adriaan J
authors.initials: AJ
authors.lastname: Minnaard
authors.forename: Steven A
authors.initials: SA
authors.lastname: Porcelli
authors.forename: D Branch
authors.initials: DB
authors.lastname: Moody
mesh_terms: D017951:Antigen Presentation / Q000502:physiology; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D018949:Antigens, CD1 / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D064429:Fatty Acid Synthases / Q000235:genetics / Q000276:immunology; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology*; D055503:Protein Multimerization; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D018949:Antigens, CD1; D001426:Bacterial Proteins; C437944:CD1C protein, human; D006023:Glycoproteins; D064429:Fatty Acid Synthases; C497999:Pks12 protein, Mycobacterium tuberculosis