Monocytes differentiating in vitro into macrophages increase their capacity to ingest particles via FcγR and CR3. Because human recombinant IL- 10 is a potent up-regulator of phagocytosis in human monocytes, we investigated whether spontaneously produced IL-10 could be a signal for the modulation of phagocytosis by cultured monocytes. We show here that culture of monocytes in the presence of anti-IL-10 mAb completely abolished up- regulation of phagocytosis of both EIgG and EIgMC3bi, suggesting a role for spontaneously produced IL-10 in the modulation of phagocytosis by cultured human monocytes. The inhibition exerted by anti-IL-10 mAb on the development of FcyR-mediated ingestion was dependent on the concomitant inhibition of FcγRIII induction in cultured cells. On the other hand, a similar down- regulation of CR3 expression was not involved in the inhibitory effect exerted by anti-IL-10 mAb on the development of CR3-mediated ingestion. Monocytes secreted detectable levels of IL-10 when cultured in medium but the concentrations of IL-10 in the supernatants decreased with length of time in culture, the decrease being completely reversed by anti-IL-10 mAb. In addition, we showed that monocytes expressed immunoreactive IL-10 on their surface and this expression increased during differentiation into macrophages. Whether this IL-10 was bound to specific membrane receptors or it was an integral membrane protein remains to be determined; however, this latter possibility is consistent with our observations that IL-10 did not elute with acid treatment and exogenous IL-10 did not increase surface staining of monocytes. Our data indicate that human mononuclear phagocytes express IL-10 on their membrane and suggest that this cytokine may represent an autocrine signal for the increased phagocytic function observed during differentiation of monocytes into macrophages.
|Titolo:||Development of phagocytic function of cultured human monocytes is regulated by cell surface IL-10.|
|Settore Scientifico Disciplinare:||Settore MED/16 - Reumatologia|
|Data di pubblicazione:||1998|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1006/cimm.1998.1349|
|Appare nelle tipologie:||01 - Articolo su periodico|