Identification of effector cell protease receptor-1. A leukocyte-distributed receptor for the serine protease factor Xa.
Mitogenesis, cell differentiation and immune-inflammatory responses are regulated by the coordinated assembly of proteases with specific cellular receptors. We have investigated the possibility that immune effector cells may express a high-affinity protease receptor. To address this hypothesis, we have generated mAb to factor V and its activated form Va, a circulating plasma protein that binds the serine protease of the coagulation cascade, factor Xa. Further, by flow microfluorimetry screening, we have isolated a panel of these mAb that recognize a surface molecule expressed on transformed monocytic cells. We now show that these mAb bind to blood monocytes, to CD3- CD16+ CD56+ NK cells, and with considerable heterogeneity, to neutrophils. A small subset of CD3+ cells (5 to 10%) was also identified by these probes and further phenotypically characterized by two-color flow microfluorimetry as predominantly coexpressing CD2, CD4 or CD8, CD57, CD11b, and alpha/beta TCR. This subset of CD3+ cells was expanded in vitro by both lectin- or Ag-specific stimulation. In addition, long term alloreactive stimulation resulted in approximately 8- to 10-fold increased expression of the molecule recognized by these mAb. Functional analyses were performed on a selected T cell clonal derivative of the transformed cell line HuT 78. These cells bound 125I-factor Xa in a specific reaction saturated at 194,000 +/- 26,000 molecules/cell with a Kd approximately 10 to 20 nM and inhibited by the mAb panel described above. These data suggest that immune effector cells express a dynamically regulated protease receptor that is immunologically related to the plasma coagulation protein factor V and its activated form Va. We propose the term effector cell protease receptor-1 to tentatively identify this molecule, and we speculate on its possible involvement in specialized protease-mediated effector functions.
Altieri
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Department of Immunology, Research Institute of Scripps Clinic, La Jolla, CA 92037.
Edgington
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D000911:Antibodies, Monoclonal / Q000276:immunology*; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex; D002460:Cell Line; D005165:Factor V / Q000276:immunology*; D015943:Factor Va / Q000276:immunology*; D015951:Factor Xa / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular; D051034:Inhibitor of Apoptosis Proteins; D016023:Integrins / Q000032:analysis; D007694:Killer Cells, Natural / Q000378:metabolism; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D011233:Precipitin Tests; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D011956:Receptors, Cell Surface / Q000276:immunology* / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D000077022:Survivin
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C107489:BIRC5 protein, human; D017252:CD3 Complex; D051034:Inhibitor of Apoptosis Proteins; D016023:Integrins; D011948:Receptors, Antigen, T-Cell; D011956:Receptors, Cell Surface; D000077022:Survivin; D015943:Factor Va; D005165:Factor V; D012697:Serine Endopeptidases; D015951:Factor Xa