SYNTHESIS OF THE FIRST COMPONENT OF HUMAN COMPLEMENT IN VITRO

Isolated segments of human colon and to a lesser extent ileum were capable of synthesizing hemolytically active C'1. This conclusion was based on the following evidence:

After elimination of C'1 from tissue with EDTA, we found that segments of the intestinal tract in short-term organ culture showed a 50–1000-fold increase in C'1 activity. The rate of production of C'1 in human intestine was highly temperature dependent; C'1 production was reversibly inhibited by puromycin and actinomycin D. Furthermore, ¹⁴C-labeled amino acids were incorporated into molecules which behaved like C'1. No significant C'1^hu synthesis was observed in isolated segments of jejunum, stomach, liver, kidney, lung, spleen, lymph node, and thymus.