NEPHELOMETRIC DETERMINATION OF RAT FIBRINOGEN AS A MARKER OF INFLAMMATORY RESPONSE

Following tissue injury or infection, the concentrations of several pl asma proteins are altered substantially. The characteristic pattern of this change is termed the acute phase response, and can be observed i n many different inflammatory situations, including surgical trauma, i njury, infections, tissue infarction and several immunologically media ted states such as temporalis arteritis, polymyalgia rheumatica and rh eumatoid arthritis. It is often of great clinical value to monitor the acute phase response in humans but the assays used to measure the acu te response in man (e.g., erythrocyte sedimentation rate and C-reactiv e protein) is less well suited for experimental studies in the rat. We have instead developed a nephelometric assay for determination of fib rinogen as a marker of the inflammatory response in rats. The assay wa s used to monitor the inflammatory response in type II collagen arthri tis in rats. This model involves the induction of severe polyarthritis and is a widely used animal model for rheumatoid arthritis (RA). Fibr inogen concentrations increased from 3.1 g/l before immunization to 10 .5,g/l 2 weeks after the immunization, after which they gradually decl ined towards normal levels. This pattern of fibrinogen alterations cor related well with the inflammatory phase of the arthritic response. Pl asma fibrinogen may thus represent a rapid and sensitive marker of the acute phase response in the rat. (C) 1997 Elsevier Science B.V.