Detection of complement activation in human serum using C5a-induced chemiluminescence of human granulocytes

The complement system can be activated by many factors, including immune complexes, leading to the generation of biologically active split products like C5a anaphylatoxin. This study presents a technique which may be used for measuring C5a activity in human serum. The tetanus-anti-tetanus immune complex and aggregated human IgG were used as model activators of the complement cascade. The C5a activity was measured by C5a-induced chemiluminescence of granulocytes; furthermore, a radioimmunoassay was used to detect the C5a peptide. There was a strongly positive correlation between the two assay systems. The described method should be useful as an alternative means of detecting complement activation in the serum of patients with inflammatory diseases.