ACTIVITY AND ACTIVATION OF THE COMPLEMENT-SYSTEM IN PATIENTS BEING OPERATED ON FOR CANCER OF THE COLON

Objective: To find out if there was any local activation of complement in the vicinity of a colonic cancer, and any fluctuation in the funct ion of the complement system during operation. Design: Prospective stu dy. Setting: One university and two district hospitals in Denmark. Sub jects: 29 selected patients undergoing emergency and elective operatio ns for colonic cancer. Interventions: Measurements of systemic and loc al complement fixation capacity and complement activation in samples o f serum or plasma taken before, during, and after operation. Main outc ome measures: Changes in complement fixation capacity and complement a ctivation during operation. Results: Haemodilution during operation ca used a significant reduction in the complement fixation capacity of se rum and in the activation of the complement system as measured by gene ration of C3c. We were unable to confirm the presence of complement in hibitors during operation. Haemodilution caused a 30% reduction in fix ation capacity of C3b (12/29 samples of serum had values more than 2SD below the mean of the reference range compared with 4/29 before opera tion). The activity of C4 was reduced by 25% during operation and the capacity of the complement system to fix C3b and C4b was restored to b aseline nine days postoperatively. Concentration of C3d was significan tly higher in serum from tumour venous blood compared with that from p eripheral blood during operation. Conclusion. The presence of compleme nt activation products in the general circulation reflects local activ ation of the complement system in the vicinity of the tumour, but this may have been influenced by tissue necrosis or subclinical infection. Haemodilution causes a significant reduction in the capacity of the c omplement system during operation, whereas inhibitory factors associat ed with the cancer or operation and anaesthesia could not be demonstra ted. We found no correlation between complement activity and clinical data.