296 IMMUNO-CATALYSIS 



and Sta'phylococcus aureus. Witebsky and Neter (1936), Neter and 

 Witebsky (1936), and Neter (1937) reported that anti-clotting factor 

 was produced by Streptococcus viridans, enterococci, pneumococci of 

 various types, some strains of Escherichia coli, Pseudomonas fjo- 

 cyaneus and others. Reed, et al. (1943) reported that six cultures of 

 CI. welchii out of thirty-three tested prevented calcium chloride from 

 clotting rabbit plasma. About the same proportion of cultures of CI. 

 novyi, CI. sefticum, CI. Sforogenes and CI. histolyticutn exhibited an 

 anti-clotting effect. The anti-clotting factor was reported by Reed, et al. 

 to be less active against guinea pig or human plasma than against rabbit 

 plasma. 



According to Dart (1936) streptococcal anti-clotting factor is not 

 specific for human fibrin, but will also prevent the clotting of isolated- 

 fibrinogen-thrombin complex from rabbit, sheep, cow and domestic 

 swines. The anti-clotting factor is not neutralized with concentrations 

 of commercial streptococcal antiserum sufficient to neutralize strepto- 

 coccal fibrinolytic factor. The fibrinolytic factor is precipitable with 

 alcohol, the anti-clotting factor remains in solution in the supernatant 

 alcohol. The anti-clotting factor recovered from alcohol is thermostable, 

 resisting heating at 100°C. for 30 minutes. 



There is lacking information concerning the specific nature and 

 action of the anti-clotting factor; also the extent of the distribution of 

 bacterial clotting factor remains undefined. 



c. The Role of Bacterial Clotting Factor in Phagocytosis and 

 Infection. In discussing the pathogenicity of a bacterium one must not 

 lose sight of various factors they elaborate in the elucidation of the 

 mechanisms of bacterial invasiveness and pathogenicity. Metabolism of 

 a bacterium producing toxins etc. in a host environment no doubt 

 plays a significant role. There are, however, accessory factors which 

 may be essential, though themselves non-toxic, for the initiation and 

 spread of an infection in a susceptible host. According to more recent 

 studies (Hale and Smith, 1945; Smith, Hale and Smith, 1947) the 

 staphylococcal plasma clotting factor is such an accessory factor in the 

 fixation of staphylococci and the production of circumscribed local 

 lesions. These investigators reported that clotting factor inhibits 

 phagocytosis. Thus, during an infection plasma clotting activity con- 

 fers upon the infective organism a first line of defense by resisting the 

 phagocytic activity of leucocytes. Under these conditions, the organism 



