Aortobifemoral Surgery Induces Complement Activation and Release of Interleukin-6 but not Tumour Necrosis Factor-alpha

The aim of the present study was to determine the inflammatory response by an extended analysis of complement in 16 patients undergoing aortobifemoral bypass surgery. The patients were randomized to recieve either a bifurcated expanded polytetrafluoroethylene graft (n = 8; group I) or a collagen-impregnated knitted Dacron graft (n = 8; group II) to determine whether differences in graft surface properties might influence the inflammatory response during and after the procedure. The following components of complement: C1q. C4, C3, C3d, C5a and terminal complement complexes were all analysed. C-reactive protein and interleukin-6 were also determined to assess the acute phase response. The complement data were corrected for haemodilution, which was assessed from α2-macroglobulin concentrations. A significant decrease of C1q (P < 0.0001) and an increase in CSa (P < 0.0005) was observed in both groups. C4 and C3 levels showed slight fluctuations in group I, whereas in group II these proteins increased significantly (P < 0.05. P < 0.005, respectively) between 2 and 7 days after surgery. Terminal complement complexes remained unchanged in both groups. Interleukin-6 levels peaked at 12–24 h and the C-reactive protein at 24–72 h. Higher interleukin-6 levels (P < 0.05) were found in group II 6h after surgery compared with group I; no release of tumour necrosis factor-alpha was identified. An early inflammatory response was found in all patients. The patterns of the complement proteins varied with a C1q depletion and a C5a increase, interpreted as complement activation. Whether the variations between the two graft groups represent any differences in graft surface properties has to be further elucidated.