title: Comparative analysis of phosphotyrosyl polypeptides in normal and leukemic human T lymphocytes activated via CD3 or CD2.
abstract: Phosphotyrosyl polypeptides induced following CD3- or CD2- specific antibody stimulation were analysed in different human T cell lines by immunoblotting or by immunoprecipitation of 32P-labelled cell lysates using a phosphotyrosine-specific monoclonal antibody. In Jurkat cells, resting peripheral T lymphocytes, T lymphoblasts, CD8+ T lymphoblasts and a CD4+ T cell clone, CD3 stimulation induced a strong but transient tyrosine phosphorylation of at least 15 polypeptides. However, in peripheral T cells and T blasts, the kinetics of phosphorylation were considerably slower than in Jurkat cells. The pattern of phosphotyrosyl polypeptides induced by CD3 stimulation was similar, although some differences were noted between normal T cells and Jurkat, especially at the level of the extent of phosphorylation. As had been previously reported for Jurkat T cells, a qualitatively similar tyrosine phosphorylation response was induced upon CD2 or CD3 stimulation in each of the analysed T cell populations, suggesting that CD3 and CD2 share a common pathway of protein tyrosine kinase (PTK) activation. In HPB. ALL leukemia T cells (which express very low levels of CD45), both CD3 and CD2 stimulation induced only very weak protein tyrosyl phosphorylation. However, a 50 kDa polypeptide, which was part of an inducible doublet in Jurkat or normal T lymphocytes, was constitutively tyrosyl-phosphorylated in the HPB. ALL line. These results suggest that there is a common pathway of early PTK activation following CD3- or CD2-mediated stimulation in mature T cells, whether they express surface CD4 or CD8, and also that the PTK may be differently regulated in different T cell populations leading to different kinetics or intensity of tyrosyl phosphorylation.
authors.affiliation: Cell Surface Biochemistry Laboratory, Imperial Cancer Research Fund, London, U.K.
authors.forename: C
authors.initials: C
authors.lastname: Boyer
authors.forename: S
authors.initials: S
authors.lastname: Ley
authors.forename: A
authors.initials: A
authors.lastname: Davies
authors.forename: M
authors.initials: M
authors.lastname: Crumpton
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D018801:CD2 Antigens; D017252:CD3 Complex / Q000276:immunology*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D010455:Peptides / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D011971:Receptors, Immunologic / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D010455:Peptides; D011971:Receptors, Immunologic; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases