Opsonic activity of human ascitic fluid: a potentially important protective mechanism against spontaneous bacterial peritonitis

Hepatology. 1985 Jul-Aug;5(4):634-7. doi: 10.1002/hep.1840050419.


The opsonic activity of 60 ascitic fluids from 47 patients was measured using a standard opsonophagocytic assay. Curve analysis of the opsonic activity compared to the ascitic fluid concentration of total protein, total hemolytic complement, C3 and C4 yielded correlation coefficients of 0.84 (p less than 0.001), 0.84 (p less than 0.001), 0.94 (p less than 0.001) and 0.92 (p less than 0.001), respectively. There appeared to be a threshold of concentration for each protein below which there was no killing of bacteria. Cirrhotic ascites had significantly (all p less than 0.001) lower concentrations of total protein and complement and less opsonic activity than noncirrhotic ascites (including malignant, cardiac and miscellaneous types). Perhaps it is the dilution of crucial antimicrobial proteins below a threshold which predisposes to spontaneous bacterial peritonitis.

MeSH terms

  • Ascites / immunology
  • Ascitic Fluid / immunology*
  • Ascitic Fluid / metabolism
  • Bacterial Infections / immunology*
  • Complement C3 / analysis
  • Complement C4 / analysis
  • Complement System Proteins / analysis
  • Heart Failure / immunology
  • Humans
  • Liver Cirrhosis / immunology
  • Neutrophils / immunology
  • Opsonin Proteins / immunology*
  • Peritonitis / immunology*
  • Phagocytosis
  • Proteins / analysis


  • Complement C3
  • Complement C4
  • Opsonin Proteins
  • Proteins
  • Complement System Proteins