title: Inhibiting HLA-B27 homodimer-driven immune cell inflammation in spondylarthritis.
abstract: OBJECTIVE
  Spondylarthritides (SpA), including ankylosing spondylitis (AS), are common inflammatory rheumatic diseases that are strongly associated with positivity for the HLA class I allotype B27. HLA-B27 normally forms complexes with β(2) -microglobulin (β(2) m) and peptide to form heterotrimers. However, an unusual characteristic of HLA-B27 is its ability to form β(2) m-free heavy chain homodimers (HLA-B27(2) ), which, unlike classic HLA-B27, bind to killer cell immunoglobulin-like receptor 3DL2 (KIR-3DL2). Binding of HLA-B27(2)  to KIR-3DL2-positive CD4+ T and natural killer (NK) cells stimulates cell survival and modulates cytokine production. This study was undertaken to produce an antibody to HLA-B27(2)  in order to confirm its expression in SpA and to inhibit its proinflammatory properties.
  
  
  METHODS
  We generated monoclonal antibodies by screening a human phage display library positively against B27(2)  and negatively against B27 heterotrimers. Specificity was tested by enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR) assay, and fluorescence-activated cell sorting (FACS) analysis of B27(2) -expressing cell lines and peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) from patients with SpA. Functional inhibition of KIR-3DL2-B27(2)  interactions was tested using cell lines and PBMCs from patients with SpA.
  
  
  RESULTS
  Monoclonal antibody HD6 specifically recognized recombinant HLA-B27(2)  by ELISA and by SPR assay. HD6 bound to cell lines expressing B27(2) . FACS revealed binding of HD6 to PBMCs and SFMCs from patients with AS but not from controls. HD6 inhibited both the binding of HLA-B27(2)  to KIR-3DL2 and the survival and proliferation of KIR-3DL2-positive NK cells. Finally, HD6 inhibited production of the proinflammatory disease-associated cytokine interleukin-17 by PBMCs from patients with AS.
  
  
  CONCLUSIONS
  These results demonstrate that antibody HD6 has potential for use in both the investigation and the treatment of AS and other B27-associated spondylarthritides.
authors.affiliation: University of Zurich, Zurich, Switzerland.
authors.forename: Sravan K
authors.initials: SK
authors.lastname: Payeli
authors.forename: Simon
authors.initials: S
authors.lastname: Kollnberger
authors.forename: Osiris
authors.initials: O
authors.lastname: Marroquin Belaunzaran
authors.forename: Markus
authors.initials: M
authors.lastname: Thiel
authors.forename: Kirsty
authors.initials: K
authors.lastname: McHugh
authors.forename: Joanna
authors.initials: J
authors.lastname: Giles
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Shaw
authors.forename: Sascha
authors.initials: S
authors.lastname: Kleber
authors.forename: Anna
authors.initials: A
authors.lastname: Ridley
authors.forename: Isabel
authors.initials: I
authors.lastname: Wong-Baeza
authors.forename: Sarah
authors.initials: S
authors.lastname: Keidel
authors.forename: Kimiko
authors.initials: K
authors.lastname: Kuroki
authors.forename: Katsumi
authors.initials: K
authors.lastname: Maenaka
authors.forename: Andreas
authors.initials: A
authors.lastname: Wadle
authors.forename: Christoph
authors.initials: C
authors.lastname: Renner
authors.forename: Paul
authors.initials: P
authors.lastname: Bowness
mesh_terms: D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D015796:HLA-B27 Antigen / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000276:immunology* / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D025241:Spondylarthritis / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D015796:HLA-B27 Antigen