PRODUCTION OF ANTIPNEUMOCOCCIC SERUM 581 



determine the suitability of the serum for concentration (Good- 

 ner 528 ). The method, however, has not proved to be accurate and 

 has fallen into disuse. 



Complement fixation. Although there appear to have been no 

 systematic studies directed toward applying complement fixation 

 as a means of serum standardization, it is a method which, at least 

 from the theoretical standpoint, might be employed. 



Bactericidal power. Tests for determining the bactericidal or 

 phagocytic power of blood have been developed in attempts to 

 measure natural or artificial immunity to pneumococci. However, 

 because of irregularities in the results, tests for bactericidal action 

 have not been adopted routinely for the standardization of thera- 

 peutic antipneumococcic serums. 



It is generally assumed that defense of the body against pneu- 

 mococcal infection depends on the neutralization of capsular poly- 

 saccharide, thus permitting phagocytosis of the organisms. De- 

 termination of the opsonic or tropic activity of serum should 

 presumably offer a valuable means of estimating therapeutic effect. 

 No in vitro method of this sort yet devised is superior to a satis- 

 factory mouse protection test. 



Antitoxic flocculation. If it is proved that antitoxic properties 

 can be imparted to antipneumococcic serum and if these properties 

 are of clinical benefit, then some in vitro method for estimating the 

 antitoxic potency of the serum will be needed. In that event, the 

 flocculation test devised by Powell* would be applicable. 



Quellung reaction. Clapp, Phillips, and Stahl (1935) 234 have 

 suggested an adaptation of the well-known Neufeld Quellung reac- 

 tion for the titration of antipneumococcic serum. The technique 

 requires relatively small amounts of materials and appears to be 

 equally applicable to all types of antipneumococcic serum. Some 

 of the difficulties involved in other methods are apparently avoided 

 in this test, but its advantages as a routine procedure have not as 

 yet been demonstrated. 



* Mentioned by Clowes, Jamieson, and Olson. 244 



