title: Evidence for protein tyrosine kinase involvement in CD6-induced T cell proliferation.
abstract: Several studies have demonstrated that addition of soluble anti-CD6 mAbs to 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated naive T cells can induce cell proliferation. We showed in the present study that cell proliferation in TPA-treated T cell cultures can be enhanced several fold when the anti-CD6 mAbs are either immobilized or crosslinked with rabbit anti-mouse immunoglobulins (RAM Ig). Using a src family protein tyrosine kinase (PTK) inhibitor, herbimycin A, the cell proliferation induced by the anti-CD6 mAb, IOR-T1, in TPA-treated T cells were effectively abolished. Analysis of the cellular proteins in these cells after crosslinking the CD6 receptor with IOR-T1 (followed by RAM Ig) in the presence of TPA resulted in an increased level of tyrosine phosphorylation. Pretreatment of native T cells with herbimycin A (0.5 and 1 microgram/ml) for 18 hr completely inhibited the tyrosine phosphorylation on cellular substrates in T cell cultures stimulated with IOR-T1/RAM Ig and TPA. Similar concentrations of herbimycin A also inhibited the increase in IL-2 mRNA expression and cell proliferation in T cell cultures after IOR-T1/RAM Ig and TPA treatment. Furthermore, the increase in cytosolic free Ca2+ concentration in naive T cells after crosslinking of the CD6 receptor with IOR-T1/RAM Ig was also inhibited by herbimycin A. Taken together, our results suggest that CD6-mediated T cell proliferation is IL-2 dependent, and involves tyrosine kinase activity which is strictly dependent on protein kinase C activation.
authors.affiliation: Departamento de Biologia, Instituto Nacional de Oncologia y Radiobiologica (INOR), La Habana, Cuba.
authors.forename: L M
authors.initials: LM
authors.lastname: Osorio
authors.forename: C
authors.initials: C
authors.lastname: Ordonez
authors.forename: C A
authors.initials: CA
authors.lastname: Garcia
authors.forename: M
authors.initials: M
authors.lastname: Jondal
authors.forename: S C
authors.initials: SC
authors.lastname: Chow
mesh_terms: D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000494:pharmacology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000494:pharmacology*; D001483:Base Sequence; D016227:Benzoquinones; D002118:Calcium / Q000378:metabolism; D003432:Cross-Linking Reagents; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008213:Lymphocyte Activation / Q000187:drug effects; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000502:physiology*; D011809:Quinones / Q000494:pharmacology; D011817:Rabbits; D017828:Rifabutin / Q000031:analogs & derivatives; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D016227:Benzoquinones; C062279:CD6 antigen; D003432:Cross-Linking Reagents; D007376:Interleukin-2; D007476:Ionophores; D047029:Lactams, Macrocyclic; D011809:Quinones; D017828:Rifabutin; D015759:Ionomycin; C020754:herbimycin; D011505:Protein-Tyrosine Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium