APPLICATION OF THE PHENOMENON 395 



mouse, results in a highly fatal and rapidly progressing infection. 

 It is suggestive from their experiments that the virulence of the 

 microorganism itself may not be enhanced. It seems more likely 

 that the mucin either paralyzes the defense of the animal or pro- 

 tects the microorganism from the natmal antibodies and phago- 

 cytes of the animal. Inasmuch as these experiments are very recent, 

 it is impossible to determine what the \'alue of these tests may be 

 in estimation of the therapeutic potency of sera. 



STUDIES ON THE PHENOMENON-NEUTRALIZING ANTIBODIES OF ANTI- 



MENINGOCOCCUS IMMUNE SERA AND THEIR USE IN CASES OF 



MENINGOCOCCUS MENINGITIS 



In 1929, before the methods were fully standardized, studies 

 on neutralizing potency of a number of batches of therapetitic 

 anti-meningococcus sera ^vere carried out, and comparisons made 

 between the agglutinating and neutralizing titers of the sera. 



Preliminary experiments established that i c.c. of a dilution 

 1:20 of a meningococcus Group III, 44B "agar washings" fil- 

 trate injected intravenously into rabbits prepared with 0.25 c.c. 

 of a dilution 1:25, elicited reactions in all rabbits tested. In the 

 neutralization experiments a dose three times greater (1.5 c.c. of 

 a dilution 1:10) was used in mixture ^vith sera variously di- 

 luted. Ten batches ^vere studied. No sera were found that w^ere 

 capable of complete neutralization of the meningococcus react- 

 ing factors in the doses employed. A number of sera, how^ever, in 

 certain dilutions were capable of inhibiting reactions in at least 

 3 out of 5 rabbits tested. As the dilution of the serum increased 

 the reactions appeared in a larger percentage of rabbits. 



It is especially interesting that no parallelism existed between 

 the neutralizing and agglutinating potencies of the therapeutic 

 sera. Thus, in some instances, sera of high neutralizing potency 

 were also of high agglutination titer. Conversely, a serum poor in 

 agglutinins was of a high neutralizing potency and a rabbit serum 

 of high agglutinating titer contained no neutralizing antibodies. 

 The lack of correlation between the neutralizino and aoxrlutinat- 

 ing titers of sera is further supported by experiments about to be 

 described. 



The discrepancy between the agglutinating and phenomenon- 

 neutralizing potencies also exists in sera for active principles of 

 microorganisms other than the meningococcus. 



According to Linton, Singh and Seal (1935) , rabbit serimi pre- 



