the present invention discloses an enzyme - linked immunosorbent assay to quantitate fluid phase terminal complement activation . upon activation to form c5b - 9 , terminal complement components express neoantigens not present in the unassembled individual components . rabbit antiserum to polymerized c9 was rendered specific for c9 neoantigenic determinants by serial immunosorbtion with human serum , human c9 , and other terminal complement components bound to sepharose . using the igg from this antiserum , a sandwich elisa was devised to bind sc5b - 9 from solution onto polystyrene plates . the elisa plates were developed with the use of goat antiserum to native c9 epitopes followed by a swine anti - goat igg alkaline phosphatase conjugate . quantitation of sc5b - 9 in solution was performed by comparing sample od to a standard curve generated with human sc5b - 9 that was purified from zymosan - activated serum . the assay is sensitive to as little as 100 ng of sc5b - 9 / ml and is useful for screening plasma , serum , cerebrospinal fluid , or other biological fluids for the presence of terminal complement cascade activation .