α2-Macroglobulin and fibrinogen modulate inflammatory edema in man

Animal experiments suggest that the response of acute-phase proteins (APPs) modulates the inflammatory reaction following tissue injury. To study this in man we investigated the relation between a number of APPs, including fibrinogen and α2-macroglobulin, and the inflammatory edema induced by a primary immunization against cholera, typhoid, and yellow fever. Vaccination induces a significant APP response; however, only α2-macroglobulin and fibrinogen were of importance to the amount of edema, measured 24 h after vaccination. High plasma levels of α2-macroglobulin strongly inhibit the amount of edema, whereas a high level of fibrinogen proved to be a stimulating factor. This holds both for the basal prevaccination levels and the postvaccination levels. The normal variation of the plasma concentration of these proteins in healthy subjects seems to be a determining factor to the amount of edema in this kind of injury.