Biosynthesis of the complement components and the regulatory proteins of the alternative complement pathway by human peripheral blood monocytes.

Abstract

Short-term cultures of human peripheral blood monocytes synthesized the alternative pathway complement components C3, factors B (B) and .hivin.D (D), and properdin, the regulatory proteins C3b inactivator (C3bINA) and .beta.1H, in addition to C2, C4 and C5. B, .hivin.D, properdin, C3bINA and C2 were detected by functional assays, whereas .beta.1H, C4, C3 and C5 could only be detected using immunochemical procedures. Immunoperoxidase localization studies showed that all cells in each culture contained each component, so it is possible that all monocytes synthesize each component. Cells of the monocyte-macrophage series form a mobile source of complement components and regulatory proteins which can be concentrated at sites of inflammation.