title: Differential expression and regulation of CD6 on T-cell subsets revealed by monoclonal antibody (MAb) CH11.
abstract: A monoclonal antibody (MAb), CH11, was developed by immunizing mice with CD4+ gammadelta T-cell receptor (TCR)+ cells. It recognized an antigen expressed in the surface membrane of T-cell lines, but not of U937, lymphoblastoid B cells (LBC), K562, Raji or Daudi cells, indicating selectivity for the T-cell lineage. In addition, it labelled 70-80% of normal peripheral blood mononuclear cells (PBMC), with high expression on the erythrocyte rosetting (E+) fraction, and low/absent expression on E- cells. However, CD4+ T cells expressed higher levels of reactivity than CD8+ or gammadelta+ T-cell receptor (TCR)+ lymphocytes in PB. Furthermore, in 7 of 10 individuals tested, 7.34+/-3.88% of unselected PBMC were CH11- CD3+ and were relatively enriched in CD8+ and in gammadelta TCR+-cells. In addition, thymic gammadelta T cells, and gammadelta lymphoproliferations from two patients were nonreactive or weakly reactive with the MAb. Activation of E+ cells with phorbol-12-myristate-13-acetate (PMA) enhanced CH11 expression uniformly, whereas activation with phytohemagglutinin (PHA) selectively down-regulated expression of the antigen on the CD8+ subset. In Western blots performed in nonreducing (NR) conditions, MAb CH11 detected a 100 kDa molecule in PBMC and Jurkat T-cell lysates. Preincubation of T cells with MAb CH11 specifically abrogated their subsequent reactivity with MAb to CD6, suggesting that MAb CH11 is recognizing an epitope of CD6. Given its function as a receptor for ligands on thymic epithelium, activated leukocytes and synoviocytes, this newly defined heterogeneity of expression and regulation of the CD6 molecule on subsets of T cells may help determine their functional repertoire in vivo.
authors.affiliation: Laboratory of Immunoregulation, Chaim Sheba Medical Center, Tel Hashomer, Israel. ibank@post.tau.ac.il
authors.forename: I
authors.initials: I
authors.lastname: Bank
authors.forename: R
authors.initials: R
authors.lastname: Dardik
authors.forename: V
authors.initials: V
authors.lastname: Levy
authors.forename: I
authors.initials: I
authors.lastname: Goldstein
authors.forename: J
authors.initials: J
authors.lastname: Shoham
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000302:isolation & purification; D015703:Antigens, CD / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D010835:Phytohemagglutinins / Q000494:pharmacology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis; D012756:Sheep; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000187:drug effects / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C062279:CD6 antigen; D010835:Phytohemagglutinins; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013755:Tetradecanoylphorbol Acetate