Clq metabolism in ulcerative colitis and Crohn's disease.

The metabolism of pure radioiodine labelled Clq has been observed in five patients with ulcerative colitis, five patients with Crohn's disease, and in five control subjects. Both the fractional catabolic rate and the synthesis rate of Clq were increased in the five patients with Crohn's disease and in four of the five patients with ulcerative colitis. The fifth patient was in remission and had a normal synthesis rate. These results support the hypothesis that complement activation plays a role in the pathogenesis of these disease states and that the increased complement activation is primarily via the classical pathway.