Interrelationship between the Early Inflammatory Response and Subsequent Fibrosis after Radiation Exposure

Abstract

The mechanistic relationships between the early inflammatory response and subsequent fibrosis seen after radiation exposure were studied in rats given X-ray doses of either 2000 or 5000 rad to standardized fields of the inner thigh. The animals were further subdivided into those receiving no additional treatment and those depleted of complement with cobra venom factor. The results were consistent with the hypothesis that 2 mechanisms were responsible for the increases in extravasation rate and vascular injury seen after irradiation. These were: cytocidal damage and chemically mediated, possibly complement-dependent, mechanisms. Both direct and indirect damage to the vasculature played a role in influencing the subsequent late-radiation-induced fibrosis.