270 IMMUNO-CATALYSIS 



mission on Acute Respiratory Diseases (1946) published the following 

 findings on: 



(1) The normal range of antifibrinolysin titers in healthy subjects; 



(2) The frequency with which /3-hemolytic streptococcal infections 

 stimulated an antifibrinolysin response; and, 



(3) The specificity of the antifibrinolysin response. 



Using a standard unit of fibrinolytic factor obtained from a Group 

 A strain of ;8-hemolytic streptococcus, a titer of 50 units or less was 

 exhibited by 66 per cent of sera collected from normal subjects, indicat- 

 ing the presence of little or no antifibrinolysin. In approximately 11 

 per cent of the normal subjects the antifibrinolysin antibodies were con- 

 sidered to be elevated in that the titer was greater than 1 50 units. That 

 the high antifibrinolysin titers observed in normal subjects resulted 

 from previous experience with /^-hemolytic streptococcus was indicated 

 by the fact that the antistreftolysin titer was usually elevated in those 

 sera which also showed high antifibrinolysin titres. Streptococcus in- 

 fections produced an antistreptolysin response more frequently than an 

 antifibrinolysin response. Of the 232 hospitalized soldiers studied wdth 

 exudative tonsilitis or pharyngitis from whom ^S-hemolytic streptococci 

 were isolated by throat culture, 151 showed an increase in antistrepto- 

 lysin antibodies, whereas in only 68 was there an increase in antifib- 

 rinolysin titre. 



Thirty-seven per cent of patients with streptococcal tonsilitis devel- 

 oped antifibrinolysin antibodies during convalescence. In this series 

 of patients, with streptococcal infections of the throat, those showing 

 an increase of antistreptolysin also showed an increase in the antifib- 

 rinolysin titer. Although the majority of these patients with 'proved 

 streptococcal infection were mildly ill, there were no obvious differ- 

 ences in the severity of illness of those patients who did or did not 

 exhibit an increase in the antifibrinolytic titer. It was found that, in 

 general, those streptococci which stimulate antifibrinolysin formation 

 in vivo, produce large amounts in vitro, while those streptococci that 

 produce small amounts of fibrinolytic factor generally failed to stimu- 

 late antibody formation. 



