Measurement of histamine, complement components and immune complexes during patient reactions to iodinated contrast material.

Studies were performed on nine patients who had just suffered urticarial or bronchospastic reactions following injection of iodinated contrast material (ICM). The parameters studied were white cell histamine, serum complement components C'3 and C'4 and circulating immune complexes. The white cells of the nine patients demonstrated an average increase of 125% in intracellular histamine over the 3-4 week period following the ICM reaction. Control volunteers averaged only a 10% change. The data implies that there was a loss of white cell histamine during the ICM reaction with replenishment during the following 3-4 week period. Complement components C'3 and C'4 were normal. Circulating antigen-antibody complexes were sought via precipitin bands in agar gel using Clq. None could be isolated following seven ICM reactions. Thus these ICM reactions appeared to release histamine without detection of circulating immune complexes and with normal levels of two major complement components.