178 CHEMISTRY OF THE IMMUNITY REACTIONS 



AGGLUTININS AND AGGLUTINATION^ 



The relation of agglutination of bacteria by the serum of immunized 

 animals to their immunity is not known, for it is not established that 

 agglutination helps in the defensive reaction. ^ Agglutinated bacteria 

 seem not to be severelj' injured by the process, and can grow vigorously 

 in agglutinative serum. Possibly agglutination favors phagoc3'tosis 

 and lessens dissemination of the infecting organisms, but it is not 

 generally considered that the influence on the com-se of infection is 

 great. ^ Agglutination, therefore, may be looked upon as an incident 

 in the infection, rather than as a definite method of resistance, and it is 

 equally well produced by immunizing with foreign cells or any foreign 

 protein masses of suitable size which contain soluble antigens. 



For the production of agglutination it is necessary that the cell 

 contain an antigen (agglutinogen) which has an affinity for the specific 

 constituent of the serum, agglutinin. Normal serum may contain 

 agglutinin;'* e. g., typhoid bacilli are sometimes agglutinated by normal 

 serum, even when it is diluted thirty times, but by immunization this 

 property can be greatly increased until agglutination may be obtained 

 with dilutions as high as one to a million. Whether normal agglutinins 

 are essential^ different from immune agglutinins is not known. ° Many 

 protein solutions, especially extracts of plant tissues and leguminous 

 seeds, cause marked non-specific hemagglutination." Likewise, bac- 

 terial extracts may agglutinate red corpuscles.^ In immunization the 

 agglutinogen, which is probably an intracellular protein, acts as a stimu- 

 lator to the formation of the specific agglutinin. Hence, when we 

 inject either extracts of cells or entire cells, we secure agglutinins, for 

 the agglutinogens are liberated from the cells upon their disintegra- 

 tion. In erythrocytes ^he agglutinogen seems to be in the stroma.^ 



We can obtain agglutinins against nearly all bacteria, including 

 non-pathogenic forms, but in varying strengths. Agglutinins are 

 found in the blood stream in the highest concentrations, but they are 



^ Bibliography given by Miiller, Oppenheimer's Handbuch der Biochemie, 1909 

 (II (1), 592: Landsteiner, ibid., p. 428; Paltauf, Kolle and Wassermarin's Hand- 

 buch., 1913 (II), 483. 



^ Bull, however, would ascribe much importance to agglutination of bacteria 

 for their removal from the circulation (Jour. Exj). Med., 1915 (22), 48-4). P\ijimoto 

 (Jour. Immunol., 1919 (4), G7) also attributes to agghitinins the jKiwer to impair 

 the glucolytic action of B. colt, but there is no evidence in his experiments that 

 it is agglutinin rather than some other serum component that is responsible. On 

 the otiicr hand Zironi (Atti accad. Lincei, 1917 (2G), 19) found that agglutination 

 does not modify reproductive or biochemical activities of bacteria. 



^ IJiaizot (0. R. Soc. Biol., 1918 (81), 350) states that it is possible to modify 

 typhoid baciUi l)v treating them with nitric acid, hydroquinone or bj'' heat, so 

 that they will jjrodiicf! immunitj' without producing agglutinins. 



* Even cold blooded animals may have normal agglutinins for bacteria and 

 mammalian corjjuscles (.see Takeiiouchi, Jour. Inf. Dis., 1918 (23), 393, 415. 



*.See Andrejew, Arb. kaiserl. (iesuntlhtsamt., 1910 (33), 84. 



« Mendel, Arch. Fisiol., 1909 (7), KiS. 



' Fiikuhara, Zeit. Immunitat., 1909 (2), 313. 



8 Chyosa, Arch. f. Ilyg., 1910 (72), 191. 



