title: The Leukocyte Immunoglobulin-Like Receptor Family Member LILRB5 Binds to HLA-Class I Heavy Chains.
abstract: OBJECTIVE
  The leukocyte immunoglobulin-like receptor (LILR) family includes inhibitory and stimulatory members which bind to classical and non-classical HLA-class I. The ligands for many LILR including LILRB5 have not yet been identified.
  
  
  METHODS
  We generated C-terminal eGFP and N-terminal FLAG-tagged fusion constructs for monitoring LILR expression. We screened for LILR binding to HLA-class I by tetramer staining of 293T cells transfected with LILRA1, A4, A5 A6 and LILRB2 and LILRB5. We also studied HLA class I tetramer binding to LILRB5 on peripheral monocyte cells. LILRB5 binding to HLA-class I heavy chains was confirmed by co-immunoprecipitation.
  
  
  RESULTS
  HLA-B27 (B27) free heavy chain (FHC) dimer but not other HLA-class I stained LILRB5-transfected 293T cells. B27 dimer binding to LILRB5 was blocked with the class I heavy chain antibody HC10 and anti-LILRB5 antisera. B27 dimers also bound to LILRB5 on peripheral monocytes. HLA-B7 and B27 heavy chains co-immunoprecipitated with LILRB5 in transduced B and rat basophil RBL cell lines.
  
  
  CONCLUSIONS
  Our findings show that class I free heavy chains are ligands for LILRB5. The unique binding specificity of LILRB5 for HLA-class I heavy chains probably results from differences in the D1 and D2 immunoglobulin-like binding domains which are distinct from other LILR which bind to β2m-associated HLA-class I.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hatano
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Shaw
authors.affiliation: RDM Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
authors.forename: Marloes
authors.initials: M
authors.lastname: Olde Nordkamp
authors.affiliation: Department of Hemato-Oncology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Shandong Jinan, Shandong, Peoples Republic of China.
authors.forename: Guosheng
authors.initials: G
authors.lastname: Jiang
authors.affiliation: RDM Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
authors.forename: Demin
authors.initials: D
authors.lastname: Li
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Botnar Research Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Kollnberger
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D002460:Cell Line; D015796:HLA-B27 Antigen / Q000378:metabolism*; D015793:HLA-B7 Antigen / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D051381:Rats; D011971:Receptors, Immunologic / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D015796:HLA-B27 Antigen; D015793:HLA-B7 Antigen; C527700:LILRB5 protein, human; D011971:Receptors, Immunologic