Complement activation is a key component in the inflammation cascade. In the present study, intestinal ischemia-reperfusion (IIR) was introduced to macaques, and the pathways of complement activation in the multiple organ dysfunction syndrome (MODS) following IIR were investigated, which may provide evidence on the mechanisms underlying the endogenous protection in systemic inflammatory response. IIR was performed by clamping superior mesenteric artery and releasing clamp in 5 macaques. Immunization rate nephelometry and CH50 total complement detection were employed to measure the serum concentration of C3, C4, C-reactive protein (CRP) and total complements. Immunocytochemistry was carried out to detect the contents of IL-1 and NF-κB in polymorphonuclear cells (PMN). Flow cytometry was done to measure the apoptosis rate of PMN. At 24 h after IIR, the amount of total complement (106.6±18.07 U/mL) was reduced to 62.1±9.52 U/mL (p<0.05). In addition, the C3 was reduced by 30% (p<0.05) but C4 remained unchanged after IIR (0.1342±0.07 vs 0.1420±0.06, P>0.05). The apoptosis rate (15.4%±1.14%) of PMN was markedly reduced (3.5%±0.53%) following IIR (p<0.05) accompanied by increased contents of IL-1 and NF-κB. Moreover, CRP was also significantly elevated after IIR (4.33±1.13 mg/L vs 17.73±0.86 mg/L; p<0.01). Following IIR, complements are activated through the alternative pathway. Complement activation fragments can inhibit the apoptosis of PMN and elevate the expressions of acute phase inflammatory proteins including CRP and IL-1, which promotes the inflammation cascade and facilitates the occurrence of MODS. Aktivacija komplemenata predstavlja ključnu komponentu inflamacijske kaskade. U ovoj studiji, kod makake majmuna izazvana je intestinalna ishemija-reperfuzija (IIR) a zatim su posle IIR istraživani putevi aktivacije komplemenata u okviru sindroma višestruke disfunkcije organa, što može doneti dokaze o mehanizmima endogene zaštite u sistemskom inflamacijskom odgovoru. IIR je izazvana stezanjem gornje mezenterične arterije i prekidanjem stiska kod pet makake majmuna. Immunization rate nefelometrija i detekcija totalnog komplementa CH50 primenjene su za merenje serumske koncentracije C3, C4, C-reaktivnog proteina (CRP) i totalnih komplemenata. Sprovedena je imunocitohemija radi utvrđivanja sadržaja IL-1 i NF-κB u polimorfonuklearnim ćelijama (PMN). Stopa apoptoze PMN izmerena je pomoću protočne citometrije. Posle 24 časa od IIR, sadržaj totalnog komplementa (106,6±18,07 U/mL) bio je snižen na 62,1±9,52 U/mL (p<0,05). Pored toga, C3 je bio snižen za 30% (p<0,05), ali je C4 ostao nepromenjen posle IIR (0,1342±0,07 prema 0,1420±0,06, P>0,05). Stopa apoptoze PMN (15,4%±1,14%) bila je značajno niža (3,5%±0,53%) posle IIR (p<0,05) uz povećan sadržaj IL-1 i NF-κB. štaviše, CRP je bio značajno povišen posle IIR (4,33±1,13 mg/L prema 17,73±0,86 mg/L; p<0,01). Posle IIR, komplementi su aktivirani preko alternativnog puta. Fragmenti aktivacije komplemenata mogu sprečiti apoptozu PMN i pojačati ekspresiju inflamacijskih proteina akutne faze, uključujući CRP i IL-1, što podstiče inflamacijsku kaskadu i olakšava nastanak sindroma višestruke disfunkcije organa.