300 IMMUNO-CATALYSIS 



more rapid than the clotting of plasma; even so the action of throm- 

 bokinase in the presence of calcium chloride was still more rapid. In 

 the absence of information concerning the quantities of various factors 

 used in these systems the differences in the rates of reactions do not 

 appear to lend much aid in the interpretation of observed effects. 



In connection with the above postulates the following observations 

 are of interest. Miale (1949) observed that sterile cell-free staphylococ- 

 cal clotting factor (' coagulase") or whole culture of staphylococci fail 

 to cause the clotting of pure fibrinogen, but would clot oxalated plasma 

 during a period of from 1 5 minutes to several hours. This indicates that 

 a reaction must take place between a plasma component (coagulase- 

 globulin) and the staphylococcal factor before fibrinogen can be con- 

 verted to fibrin. Progressive removal of calcium in no way interferes 

 with this clotting of plasma by either staphylococcal factor or when it 

 is in "combination" with the plasma component, even when the plasma 

 has been rendered non-clottable by an excess of thromboplastin. It 

 would mean that the effect of staphylococcal factor differs basically 

 from the activation of prothrombin to thrombin, calcium ion being 

 essential for the latter reaction. This conclusion was supported by the 

 failure of heparin, azo dyes (chlorazol fast pink, Nat. Aniline, C. I. 

 1^353), and soluble fluorides (decalcifying agent) to interfere with the 

 clotting in the presence of staphylococcal factor and plasma globulin 

 co-factor, since heparin is known to inhibit thrombin activity and the 

 activation of prothrombin, and the azo dyes are assumed to inhibit, 

 in vivo and in vitro, thromboplastin. 



f. Properties of Clotting Factor and Activator Substance and 

 Their Possible Role in Fibrin Clot Formation. The above cited inter- 

 pretations offered by Smith and Hale are difficult to accept and appear 

 to be contradictable by the following considerations. The staphylococcal 

 clotting factor is heat-stable, its antigenicity has been disputed and 

 claimed* and therefore appears to be a substance of unknown nature. 

 As such it does not appear to warrant the assumption that it is a 



*Tager and Hale (1948) suggested that staphylococcal clotting factor is antigenic 

 for some rabbits. Three of the nine rabbits which received a long course of inocula- 

 tions with a highly purified clotting-factor possessed sera which retarded considerably 

 the clotting time, showed complement fixation titer, and colloidal agglutinating prop- 

 erty. For the demonstration of these properties in these antisera, the presence of alpha 

 hemolysin in the inoculated material was a necessary condition. These findings do 

 not, however, interfere with the discussion which will follow. 



