title: Effects of p56lck deficiency on the growth and cytolytic effector function of an interleukin-2-dependent cytotoxic T-cell line.
abstract: The growth, differentiation, and functional activities of antigen-stimulated T lymphocytes are regulated by the interaction of the T-cell-derived cytokine, interleukin-2 (IL-2), with the high-affinity IL-2 receptor (IL-2R). IL-2R occupancy initiates a rapid increase in intracellular protein tyrosine phosphorylation, suggesting that a receptor-coupled protein tyrosine kinase (PTK) serves as a proximal signaling element for the IL-2R. Previous studies implicated the src-family kinase, p56lck, as a potential IL-2R-linked signal transducer. In this study, we have characterized a spontaneous variant of the IL-2-dependent cytotoxic T-cell line, CTLL-2, which contains no detectable lck-derived mRNA transcripts, protein, or PTK activity. The p56lck-deficient CTLL-2 cells retained strict dependence on IL-2 for both viability and growth, indicating that p56lck activity was not required for the transduction of IL-2-mediated mitogenic signals. However, the p56lck-deficient cells exhibited a moderate decrease in their rate of IL-2-dependent proliferation. In contrast to this relatively modest proliferative defect, the p56lck-deficient cell line displayed a profound reduction in T-cell antigen receptor-dependent cytolytic effector functions. Both the proliferative and the cytolytic defects observed in the p56lck-deficient cells were completely reversed by transfection of these cells with a wild-type lck expression vector. These results indicate that p56lck expression is not obligatory for IL-2-mediated T-cell growth stimulation; however, this PTK plays a central role in the generation T-cell-mediated cytotoxic responses.
authors.affiliation: Department of Immunology, Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: L
authors.initials: L
authors.lastname: Karnitz
authors.forename: S L
authors.initials: SL
authors.lastname: Sutor
authors.forename: T
authors.initials: T
authors.lastname: Torigoe
authors.forename: J C
authors.initials: JC
authors.lastname: Reed
authors.forename: M P
authors.initials: MP
authors.lastname: Bell
authors.forename: D J
authors.initials: DJ
authors.lastname: McKean
authors.forename: P J
authors.initials: PJ
authors.lastname: Leibson
authors.forename: R T
authors.initials: RT
authors.lastname: Abraham
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002455:Cell Division; D003001:Cloning, Molecular; D003602:Cytotoxicity, Immunologic; D007376:Interleukin-2 / Q000502:physiology*; D007700:Kinetics; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051379:Mice; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000172:deficiency* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology*; D014162:Transfection
chemical_list: D007376:Interleukin-2; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)