title: CD5+B cells: differential capping and modulation of IgM and CD5.
abstract: CD5 is associated with the B-cell antigen receptor (BcR) complex. As an approach to understanding its role in B-cell function, the authors investigated the capping and modulation of CD5 and surface IgM (sIgM). Tonsillar B cells were treated with anti-IgM or anti-CD5 antibodies, capping examined after 1 h (by fluorescence microscopy) and modulation after 24 h (by flow cytometry). CD5 co-capped and co-modulated with sIgM. Of various drugs tested, only the protein tyrosine kinase inhibitor (genistein) had any effect on capping and co-capping. Capping of sIgM (and co-capping of CD5) but not capping of CD5 (or co-capping of sIgM) was inhibited by genistein. None of the other drugs affecting PKC or cytoskeletal structures (colchicine and cytochalasin D) had any effect. However, the PKC inhibitors, staurosporine and H-7, inhibited the modulation of sIgM by anti-IgM but not CD5 by anti-CD5. In contrast, PKC activators, PMA and mezerein, inhibited modulation of CD5 by anti-CD5 but not sIgM by anti-IgM. This suggests that direct ligation of CD5 utilizes different signalling pathways compared with sIgM. It seems likely that in CD5+ cells, interaction of CD5 with its ligand CD72 modulates signals transmitted through the BcR.
authors.affiliation: Brest University Medical School, France.
authors.forename: C
authors.initials: C
authors.lastname: Jamin
authors.forename: P M
authors.initials: PM
authors.lastname: Lydyard
authors.forename: R
authors.initials: R
authors.lastname: Le Corre
authors.forename: P Y
authors.initials: PY
authors.lastname: Youinou
mesh_terms: D000911:Antibodies, Monoclonal; D018941:Antigens, CD19 / Q000276:immunology; D001402:B-Lymphocytes / Q000502:physiology*; D018956:CD5 Antigens / Q000502:physiology*; D002273:Carcinogens / Q000494:pharmacology; D002675:Child, Preschool; D003599:Cytoskeleton / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D019833:Genistein; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D007152:Immunologic Capping / Q000187:drug effects; D007529:Isoflavones / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D000911:Antibodies, Monoclonal; D018941:Antigens, CD19; D018956:CD5 Antigens; D002273:Carcinogens; D004791:Enzyme Inhibitors; D007075:Immunoglobulin M; D007529:Isoflavones; D011947:Receptors, Antigen, B-Cell; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C