IMMUNOLOGICAL BEHAVIOR II7 



processes essentially consisting of two phases: 1. Flocculation ol 

 the antioenic components of the bacterial hltrate by imnunie 

 serum with adsorjjtion of the active principles by these complexes. 

 2. Neutralization of the active principles in these precipitates. 



It is difficult to exjjlain the fact that, on the one hand, as to 

 be shown later, certain precipitates formed throuoh tlie inter- 

 action of certain antigens with antibodies, possess reacting po- 

 tency ^vhilst, on the other liand, precipitates residting from the 

 interaction of B. typhosus with innmuie sera not only do not con- 

 tribute to the reacting potency of the mixtiue. but are able to 

 neutralize the actixe |)rinciples of the filtrate which they adsorb. 

 The differences most likely depend on the strength of the luiion 

 between the antibody and the active ])rincij)les. This, in turn, 

 may be conditioned by the concentration of the antibodies in the 

 immune serum or by the degree of interference of other antigenic 

 components in the filtrates. The inhibitory effects of multiple an- 

 tigens on the antigen -j-antibody interaction were demonstrated 

 by the work of W'eil, Bayne- Jones, Linossier and Lemoine, Eisen- 

 berg, Ascoli, von Dungern, Zinsser, Wells, Opie, and others 

 (quoted by Zinsser, 1931). 



NEUTRALIZATION OF ACTIVE PRINCIPLES 



IN "multiple proportions' 



"Multij^le proportion" neutralization of active principles of 

 the phenomenon was clearly demonstrated with B. typJiosus fil- 

 trates inasmuch as immune anti-typhoid sera of high potency xvere 

 available. A typical example xvhich xvas consistently repeated xvith 

 many batches of different B. txphosiis culture filtrates is cited 

 below: 



.A'o. of neutralized Approximate 



Amount of ant i- B. typhosus /•?- Multiples of multiples of 



typhoid serum acting factors serum used neutralization 



0.1 c.c 75 



O. 25 c.c 150 2.5 2 



I c.c 550 9 7 



It is of special interest that similarly to the dij)htheria toxin- 

 antitoxin neutralization, the use of increasing midtiples of serum 

 brings about a roughly proportionate increase in the amount of 

 filtrate neutralized. The multiple jsroportion neutralization is 

 also brought out by experiments on concentration and pinifica- 

 tion of anti-typhoid horse serum (Reiner and Shwartzman, 1930) . 



