title: Expression of soluble CD137 correlates with activation-induced cell death of lymphocytes.
abstract: CD137 is a member of the tumour necrosis factor receptor family which delivers a potent co-stimulatory signal to T lymphocytes. Soluble forms of CD137 (sCD137) can be found at enhanced levels in sera of patients with rheumatoid arthritis. Here we show that expression of sCD137 lags behind that of membrane-bound CD137 (mCD137) by about 24 h. In fully activated lymphocytes, time of maximum increase and level of expression of sCD137 were at day 2 and 3, respectively. Expression of sCD137 in lymphocytes requires strong activation, and levels of sCD137 correlate negatively with lymphocyte proliferation and positively with the degree of activation-induced cell death caused by mitogen overstimulation. Since activation of lymphocytes through membrane-bound CD137 delivers a potent stimulatory signal, sCD137 may provide a negative control mechanism for immune responses.
authors.affiliation: Department of Pathology, University of Regensburg, Regensburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Michel
authors.forename: H
authors.initials: H
authors.lastname: Schwarz
mesh_terms: D015703:Antigens, CD; D000001:Calcimycin / Q000494:pharmacology; D016923:Cell Death; D002455:Cell Division; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology*; D010835:Phytohemagglutinins; D020033:Protein Isoforms / Q000235:genetics; D017475:Receptors, Nerve Growth Factor / Q000235:genetics*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
chemical_list: D015703:Antigens, CD; D010835:Phytohemagglutinins; D020033:Protein Isoforms; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505714:TNFRSF9 protein, human; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate