Involvement of CD4 in interleukin-6 secretion by U937 monocytic cells stimulated with the lectin jacalin.
The lectin jacalin is mitogenic for CD4 expressing T lymphocytes, interacts with the CD4 molecule, and inhibits HIV infection of CD4+ cells. In the present study the effect of jacalin was tested on cells from the monocyte/macrophage lineage that also express the CD4 molecule. We used CD4+ promyelomonocytic U937 cells differentiated towards the monocytic/macrophage lineage with either a mixture of two physiological agents, retinoic acid (RA) and 1 alpha,25-dihydroxyvitamin D3 (VD), or the exogenous drug phorbol myristate acetate (PMA). The cells resulting from these treatments differed in term of CD4 expression. We focused our attention on interleukin-6 (IL-6) production, which implies an activation of the cells differentiated along both pathways. In CD4+ RA/VD-treated cells, jacalin induced a 10-fold higher IL-6 secretion than did lipopolysaccharide (LPS). This jacalin-induced IL-6 production was inhibited by agents interacting with CD4 (anti-CD4 mAbs and HIV recombinant gp120) or by recombinant soluble CD4. In contrast, the CD4- PMA-differentiated U937 cells did not secrete any IL-6 upon jacalin treatment, while they demonstrated a response to LPS similar to that of the RA/VD-differentiated cells. Together with the fact that jacalin interacts with CD4, these results provide evidence of the involvement of a CD4 dependent pathway in IL-6 production.
Taimi
M
M
INSERM U65, Université Montpellier II, Sciences et Techniques du Languedoc, France.
Dornand
J
J
Nicolas
M
M
Marti
J
J
Favero
J
J
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000502:physiology*; D001681:Biological Assay; D015704:CD4 Antigens / Q000502:physiology*; D002117:Calcitriol / Q000494:pharmacology; D002454:Cell Differentiation; D002460:Cell Line; D005434:Flow Cytometry; D015699:HIV Envelope Protein gp120 / Q000494:pharmacology; D006801:Humans; D007369:Interferon Inducers / Q000494:pharmacology*; D007375:Interleukin-1 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000378:metabolism; D037102:Lectins / Q000494:pharmacology*; D015473:Leukemia, Promyelocytic, Acute; D008070:Lipopolysaccharides / Q000494:pharmacology; D008163:Luminescent Measurements; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D037121:Plant Lectins; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D007369:Interferon Inducers; D007375:Interleukin-1; D015850:Interleukin-6; D037102:Lectins; D008070:Lipopolysaccharides; D037121:Plant Lectins; D011994:Recombinant Proteins; C043696:jacalin; D014212:Tretinoin; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate