8i6 AGGLUTININS AND THEIR APPLICATIONS 



sociation of agglutinated red blood cells and their specific serum was possible by heat- 

 ing from 50° to 60° C.; on cooling, the agglutination reappears, to disappear again on 

 heating. If agglutinated bacteria are treated with a dilute soda solution, partial dis- 

 sociation with liberation of the antibody occurs, according to Hahn and Tromsdorflf.' 



Bordet has conceived (1899) the reaction of agglutination as consisting of two 

 phases or of two successive phenomena. The first is an immune reaction, an antibody- 

 antigen union. This consists in the formation of a complex resulting from 'Tinter- 

 vention des afhnites specifiques" (Bordet). The second phase is physico-chemical^ 

 the clumping or aggregation of sensitized bacteria. This latter is, according to Bordet, 

 agglutination proper. In 1899 Bordet observed that the higher the concentration of 

 agglutinin in a serum the greater is the susceptibility of the antigen-agglutinin com- 

 plex to the clumping action of salt (electrolyte). It was further demonstrated by him 

 that this action occurred only in the presence of an electrolyte, Bordet summarized 

 his observations as follows: 



En resume, il resulte de ces faits que ragglutination, phenomena si frappant et qu'on 

 croirait si caracteristique, est un processus en realite secondaire. L'essentiel au point de vue 

 de I'immunite c'est union de Tanticorps a I'antigene; c'est a ce moment que la specificite 

 intervient. Le fait que certains antigenes acquierent, en se sondant a leur anticorps, cette 

 qualite d'ailleurs tres banale d'etre flocculables par les electrolytes est theoriquement acces- 

 soire. Mais il attire vivement I'attention parcequ'il rend la reaction tres perceptible a nos sens, 

 et c'est pourquoi I'anticorps en jeu s'appelle agglutinine lorsqu'il s'agit de pareils antigenes. 



The functional significance of agglutinins in infectious processes is probably sub- 

 sidiary. Certainly in diseases such as anthrax the agglutinating power of the serum 

 of an animal is not an index of the degree of resistance to this infection, as Gengou 

 was the first to show. The earlier view of Gruber and others that agglutinins possess 

 protective or therapeutic properties has been discarded generally. Widal and Sicard 

 showed that relapses occurred in patients suffering from typhoid fever even when the 

 concentration of agglutinins in their blood was greatest. BulP has shown experi- 

 mentally that agglutination occurs in vivo. It was observed by this investigator, as it 

 had been earlier by Besredka,^ that preliminary agglutination favored subsequent 

 phagocytosis. Bull found that agglutinated bacteria are promptly removed from the 

 circulation in experimental animals, and in consequence bacteremia does not ensue. 

 As a result of the work of Besredka and Bull, it may be argued that agglutination in 

 certain infections at least favors phagocytosis and, if this is the case, is part of the 

 protective mechanism in such infections. This point deserves further exploration,-* 



AGGLUTINATION PROCEDURES 



It is not our purpose to describe the precise details of the technical procedures 

 adopted in carrying out methods of demonstrating agglutination. Such instructions 

 may be found in textbooks on bacteriology or serology. We wish, however, to indicate 

 in outline these methods and to comment upon certain of their salient features. 



■ Ibid. 



' Bull, C. G.: /. Exper. Med., 22, 484. 1915. 



i Besredka, A.: Ann. de Vlnsl. Pasteitr, 15, 209. 1901. 



■t See chap, lix, by Dr. Bailey, in this volume. 



