title: Butyrophilin 3A1 plays an essential role in prenyl pyrophosphate stimulation of human Vγ2Vδ2 T cells.
abstract: Most human γδ T cells express Vγ2Vδ2 TCRs and play important roles in microbial and tumor immunity. Vγ2Vδ2 T cells are stimulated by self- and foreign prenyl pyrophosphate intermediates in isoprenoid synthesis. However, little is known about the molecular basis for this stimulation. We find that a mAb specific for butyrophilin 3 (BTN3)/CD277 Ig superfamily proteins mimics prenyl pyrophosphates. The 20.1 mAb stimulated Vγ2Vδ2 T cell clones regardless of their functional phenotype or developmental origin and selectively expanded blood Vγ2Vδ2 T cells. The γδ TCR mediates 20.1 mAb stimulation because IL-2 is released by β(-) Jurkat cells transfected with Vγ2Vδ2 TCRs. 20.1 stimulation was not due to isopentenyl pyrophosphate (IPP) accumulation because 20.1 treatment of APC did not increase IPP levels. In addition, stimulation was not inhibited by statin treatment, which blocks IPP production. Importantly, small interfering RNA knockdown of BTN3A1 abolished stimulation by IPP that could be restored by re-expression of BTN3A1 but not by BTN3A2 or BTN3A3. Rhesus monkey and baboon APC presented HMBPP and 20.1 to human Vγ2Vδ2 T cells despite amino acid differences in BTN3A1 that localize to its outer surface. This suggests that the conserved inner and/or top surfaces of BTN3A1 interact with its counterreceptor. Although no binding site exists on the BTN3A1 extracellular domains, a model of the intracellular B30.2 domain predicts a basic pocket on its binding surface. However, BTN3A1 did not preferentially bind a photoaffinity prenyl pyrophosphate. Thus, BTN3A1 is required for stimulation by prenyl pyrophosphates but does not bind the intermediates with high affinity.
authors.affiliation: Division of Immunology, Department of Internal Medicine, Interdisciplinary Graduate Program in Immunology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Olivier
authors.initials: O
authors.lastname: Henry
authors.forename: Mark D
authors.initials: MD
authors.lastname: Distefano
authors.forename: Yen-Chih
authors.initials: YC
authors.lastname: Wang
authors.forename: Johanna
authors.initials: J
authors.lastname: Räikkönen
authors.forename: Jukka
authors.initials: J
authors.lastname: Mönkkönen
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Craig T
authors.initials: CT
authors.lastname: Morita
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D001666:Binding Sites, Antibody; D000071797:Butyrophilins; D002460:Cell Line; D006367:HeLa Cells; D045782:Hemiterpenes / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation; D008253:Macaca mulatta; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds / Q000276:immunology*; D010215:Papio; D034622:RNA Interference; D034741:RNA, Small Interfering; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology; D016415:Sequence Alignment; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D013729:Terpenes
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C558381:BTN3A1 protein, human; C576586:BTN3A2 protein, human; D000071797:Butyrophilins; D045782:Hemiterpenes; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009943:Organophosphorus Compounds; D034741:RNA, Small Interfering; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013729:Terpenes; C004809:isopentenyl pyrophosphate