Role of 55- and 75-kDa TNF receptors in the potentiation of Fc-mediated phagocytosis in human neutrophils.

Human neutrophils respond with an increased phagocytosis when exposed to TNF. Two types of TNF receptors have been identified, namely 55 kDa (TR55) and 75 kDa (TR75). We addressed the problem of the role of these receptors in the priming effect of TNF. By using monoclonal antibodies (MoAbs) directed either against TR55 or TR75, we have shown that 1) only TR55 is the signaling receptor for the potentiation of Fc-mediated phagocytosis and upregulation of beta 2-integrin CD11b/CD18; 2) TR75 may control the function of TR55 by regulating the binding of TNF to the signaling receptor.