Reaction to radiographic contrast agents: new developments in etiology.

Although a significant amount of histamine is released into plasma during contrast media injections, there still is no evidence to support an immunologic basis underlying contrast media reactions. This study supports previous observations that suggest in vitro leucocyte challenge may be of predictive value in contrast media reactions. Lassar's study in dogs and this study in humans clearly shows that complement activation by alternative pathway occurs during contrast agent administration. However, pathophysiological significance of this observation is not clear.