Complement fixation kalma ce da ake amfani da ita a fannin rigakafi kuma tana nufin wani tsari wanda tsarin haɗin gwiwa, rukunin sunadaran da ke cikin jini wanda ke taimakawa wajen lalata ƙwayoyin cuta masu mamayewa da ƙwayoyin cuta na waje, ya zama “gyara” zuwa hadadden antigen-antibody, wanda ya haifar da kunnawar cascade na complement da kuma lalata abin da ke gaba. Haka kuma kalmar tana iya komawa ga gwajin dakin gwaje-gwaje da ke auna samu da adadin maganin kashe kwayoyin cuta a cikin jinin majiyyaci, wanda zai iya taimakawa wajen gano wasu cututtuka da cututtuka na autoimmune.