Down-Regulation and Release of CD14 On Human Monocytes by IL-4 Depends on the Presence of Serum Or GM-CSF
IL-4 induces down-regulation of CD14 expression on human monocytes only when the cells are cultured with serum. In serum-free cultures we failed to down-regulate CD14 by IL-4. Instead of serum, GM-CSF was required as a co-factor to restore the regulatory effect of IL-4 on CD14-expression. After 4 days of culture human monocytes were quantitatively CD14-negative as determined by flow-cytometry. On day 6, high amounts of CD14 molecules were detected in the SUP of these cultures, whereas intracellular immunofluorescence staining revealed no detectable CD14 in cytokine-treated monocytes. Thus, CD14 is lost by down-regulation (as shown by others) as well as by delivery into the medium. We previously hypothesized that dendritic cells may originate from monocytes. Our present finding support that one of the key markers, distinguishing monocytes/macrophages from dendritic cells, can be lost upon physiological stimuli.
KeywordsCD14 Expression Human Monocyte CD14 Molecule Soluble CD14 Accessory Cell
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- 1.R.A. Musson, Human serum induces maturation of human monocytes in vitro, Am. J. Pathol. III: 331 (1983).Google Scholar
- 9.J.M. Alvaro-Garcia, N.J. Zvaifler, and G.S. Firestein, Cytokines in chronic inflammatory arthritis. VI. Granulocyte/macrophage colony stimulating factor-mediated induction class II MHC antigen on human monocytes: a possible role in rheumatoid arthritis, J. Exp. Med. 170: 865 (1989).CrossRefGoogle Scholar
- 11.M.J. Elliot, M.A. Vadas, J.M. Eglington, L.S. Park, L. Bik-To, G. Cleland, S.C. Clark, and A.F. Lopez, Recombinant human interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) show common biological effects and binding characteristics on human monocytes, Blood 74: 2049 (1989).Google Scholar
- 13.N.A. Nicola and M. Vadas, in: “Oncogenes and Growth Factors,” R.A. Bradshaw and S. Prentis, eds., Elsevier Science Publishers, New York (1987).Google Scholar