title: Increased enzymatic activity of the T-cell antigen receptor-associated fyn protein tyrosine kinase in asymptomatic patients infected with the human immunodeficiency virus.
abstract: The immune system of patients infected with human immunodeficiency virus (HIV) is in a state of chronic activation; however, the nature of HIV-related immune activation is unknown. As normal T-cell activation involves early tyrosine phosphorylation induced by the T-cell antigen receptor-associated src-family protein tyrosine kinase p59(fyn(T)) (Fyn), we examined a potential role for this kinase in HIV-related immune dysfunction. We determined the relative specific kinase activity of Fyn in lysates of peripheral blood mononuclear cells from 47 normal control individuals tested negative for HIV-1 and -2, human T-cell lymphotropic virus Type I, hepatitis B virus (HBV), hepatitis C virus (HCV), and syphilis; 14 asymptomatic HIV-infected patients having near-normal CD4+ T-cell counts (350 to 980 CD4+ cells/microL); 4 patients with symptomatic acquired immunodeficiency syndrome (AIDS) (<30 CD4+ cells/microL); 13 patients having chronic infection with HBV (6 patients) or HCV (7 patients); and 6 patients with systemic lupus erythematosis (SLE). All patients with asymptomatic HIV disease were shown to have a profound increase (mean increase of 19-fold; range threefold to 56-fold increase; p = 1.33 x 10(-9)) in the relative specific kinase activity of Fyn compared to uninfected controls or patients with hepatitis or SLE. In contrast, patients with AIDS had an Fyn-specific kinase activity that was much less affected (mean increase of threefold; range onefold to sevenfold increase; p = 1.30 x 10(-5)). It was further shown that HIV infection affects the Fyn-specific kinase activity in CD8+-enriched cells, suggesting abnormal Fyn activity in both CD8+ as well as CD4+ T lymphocytes. Initial results implicate a role for the CSK protein tyrosine kinase as responsible for the abnormal Fyn kinase activity observed in HIV-infected patients. These data indicate early and chronic activation of Fyn as a unique HIV-related effect that has the potential to be diagnostic for early HIV infection and/or may serve as a prognostic indicator for advancement to full-blown AIDS. More importantly, sustained activation of the protein tyrosine kinase associated with T-cell antigen receptor function may result in, or contribute to, the immunopathogenic effects associated with HIV infection.
authors.affiliation: Department of Oncology Research, The Toronto Hospital Research Institute, Toronto, Ontario, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Phipps
authors.forename: S
authors.initials: S
authors.lastname: Yousefi
authors.forename: D R
authors.initials: DR
authors.lastname: Branch
mesh_terms: D004789:Enzyme Activation / Q000276:immunology; D015658:HIV Infections / Q000201:enzymology* / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D011505:Protein-Tyrosine Kinases / Q000276:immunology*; D011518:Proto-Oncogene Proteins / Q000276:immunology*; D051076:Proto-Oncogene Proteins c-fyn; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology
chemical_list: D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn