Human serum amyloid P component binds to peripheral blood monocytes

Abstract

The binding of human serum amyloid P component (SAP) to blood cells and monocyte-derived dendritic cells was investigated by flow cytometry. Monocytes bound biotinylated SAP with avidity in a dose-dependent and saturable manner. By contrast, the binding of SAP to monocyte-derived dendritic cells was weak. No binding to erythrocytes, NK cells, T lymphocytes or B lymphocytes could be detected. The SAP-monocyte interaction was calcium-independent and readily inhibited by C1q. SAP was nonmitogenic for human mononuclear cells and had no apparent influence on lymphocyte proliferation induced by mitogenic lectins. We speculate that binding of SAP by monocytes could be of physiological relevance at extravascular sites by influencing complement regulation. © 2006 The Authors.