title: Interferon-gamma inhibits CD44-hyaluronan interactions in normal human B lymphocytes.
abstract: The interaction of CD44 with its ligand hyaluronan (HA) plays a vital role in lymphopoiesis, lymphocyte homing, T cell activation, and metastasis. This study addresses the effect of cytokines involved in B cell growth on CD44-HA interactions in normal human B cells. Activation of B lymphocytes with LPS, pokeweed mitogen, or anti-IgM antibodies with or without IL-2 or IL-4 failed to induce HA adhesion. Stimulation of B cells with the phorbol ester PMA, however, induced strong HA recognition, which was inhibited by IFN-gamma and to some extent by IL-4. Investigation of the potential molecular mechanism involved revealed that PMA-induced HA adhesion correlated with enhanced expression of CD44-H- and V6-containing isoforms, as determined by flow cytometry, and the differential induction of V4- and V5-containing isoforms, as determined by reverse transcriptase-based polymerase chain reaction analysis. The inhibition of PMA-induced adhesion by IFN-gamma and IL-4 correlated with the downregulation of CD44 H expression and altered usage of exons V4 and V5. However, changes in the electrophoretic mobility of CD44 proteins, as a measure of posttranslational modifications, were not detected in response to PMA and IFN-gamma or PMA and IL-4. These results suggest that the inhibition of PMA-induced HA adhesion by IFN-gamma and IL-4 may influence B cell migration through their ability to downregulate CD44-HA interactions.
authors.affiliation: Faculty of Medicine, University of Ottawa, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Kryworuchko
authors.forename: F
authors.initials: F
authors.lastname: Diaz-Mitoma
authors.forename: A
authors.initials: A
authors.lastname: Kumar
mesh_terms: D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism* / Q000494:pharmacology; D015847:Interleukin-4 / Q000378:metabolism / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D018960:Hyaluronan Receptors; D008934:Mitogens; D020033:Protein Isoforms; D015847:Interleukin-4; D007371:Interferon-gamma; D006820:Hyaluronic Acid; D013755:Tetradecanoylphorbol Acetate