title: Pertussis toxin effects on T lymphocytes are mediated through CD3 and not by pertussis toxin catalyzed modification of a G protein.
abstract: Pertussis toxin (PT) has been shown to have a variety of effects on T lymphocyte function, and its activity has been used to suggest the involvement of a G protein in the early events of T lymphocyte activation. In this report, the effects of PT on T lymphocytes have been investigated in detail. PT at a concentration of 10 micrograms/ml rapidly stimulated early events that are normally induced by occupancy of the TCR complex in Jurkat cells and cloned, murine CTL including increased intracellular Ca2+ concentration, serine esterase release, and induction of Ag non-specific target cell lysis. However, 1-h treatment with this concentration of PT induced a state that was refractory to further receptor stimulation in Jurkat cells but not cloned CTL although substrate membrane proteins were modified to a similar extent in both cell lines. The functional effects of PT were mimicked by the B oligomer of PT which did not, however, catalyze ADP-ribosylation of membrane proteins. In addition, overnight exposure of Jurkat cells to a lower concentration of PT also modified substrate membrane proteins but did not inhibit receptor stimulation. These findings indicate that PT catalyzed ADP-ribosylation of a G protein does not account for the actions of the toxin on T lymphocytes. Finally, direct stimulation of increased intracellular Ca2+ concentration by PT and the B oligomer only occurred in T lymphocytes expressing CD3. This suggests that the mitogenic effect of PT holotoxin is mediated by the interaction of the B oligomer with CD3 and that this may account for many of the effects of PT holotoxin both in vivo and in vitro.
authors.affiliation: Department of Pathology, University of Virginia Health Sciences Center, Charlottesville 22908.
authors.forename: L S
authors.initials: LS
authors.lastname: Gray
authors.forename: K S
authors.initials: KS
authors.lastname: Huber
authors.forename: M C
authors.initials: MC
authors.lastname: Gray
authors.forename: E L
authors.initials: EL
authors.lastname: Hewlett
authors.forename: V H
authors.initials: VH
authors.lastname: Engelhard
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D001667:Binding, Competitive; D017252:CD3 Complex; D002118:Calcium / Q000096:biosynthesis; D002384:Catalysis; D002460:Cell Line; D002999:Clone Cells / Q000145:classification / Q000201:enzymology / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D053804:Granzymes; D006801:Humans; D037342:Pertussis Toxin; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D012697:Serine Endopeptidases / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000145:classification / Q000201:enzymology / Q000276:immunology*; D010566:Virulence Factors, Bordetella / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D053804:Granzymes; D012697:Serine Endopeptidases; C509212:GZMA protein, human; D019204:GTP-Binding Proteins; D002118:Calcium