Cell-membrane activation of macrophage function.

Abstract

A number of short-term macrophage functions are stimulated immediately on contact of suitable external materials with the macrophage plasma membrane. These include locomotion and chemotaxis, phagocytosis, and exocytosis of lysosomal hydrolases. They are probably contractile events and may be initiated by a transient increase in permeability to divalent cations either of the plasma membrane or of hypothetical intracellular cations stores. Such permeability changes may follow interaction of hydrophobic substances with the membrane bilayer or follow contact with substances which induce clustering of membrane proteins. It is conjectured that similar substances might induce long-term events such as DNA and protein synthesis, mitosis and activation of cytotoxic function in macrophages, but that to do this, contact of the substance with the macrophage must be prolonged.