208 CHEMISTRY OF THE IMMUNITY REACTIONS 



separated again from the complement by simple chemical precipita- 

 tion. Acids stronger than CO2 and of the higher saturated or un- 

 saturated fatty acid series, inactivate complement in strengths greater 

 than n/40, and alkalies are equally inhibitive.^' Ultraviolet rays 

 destroy complement. ^^ Sherwood^^ has made a study of various sub- 

 stances that may be present in the blood in excessive amounts during 

 pathological conditions, such as CO2, lactic acid, acetone, etc., and 

 finds that they interfere seriously with the action of complement, 

 which suggests that they may favor infection or interfere with recovery 

 from infection. 



Presumably the complement is a protein, for it has antigenic prop- 

 erties, so that immunization with sera containing either complement 

 or complementoid causes anticomplement activity in the blood of the 

 immune animal. Also, it is destroyed by trypsin free from lipase, ^^ 

 and, like other colloids, is readily adsorbed by surfaces; hke enzymes, 

 complement is destroyed by shaking, ^^ and gradually disappears on 

 standing. There are some striking resemblances between the be- 

 havior of complement and of certain compounds of protein with soaps 

 and lipoids, as pointed out especially by Noguchi, but that these are 

 identical with true complement is doubtful. (See Hemolysis.) Its 

 colloid nature is attested by the large loss when complement is filtered 

 through Berkefeld filters. ^*^ 



A careful review of the evidence has led Liefmann^'^ to the conclu- 

 sion that the reaction of complement to sensitized corpuscles is more 

 hke that of ferment to substrate than of antigen to antibod3^ In its 

 effect of dissolving bacteria (and also other cells against which animals 

 may have been immunized) co77iplement resembles the enzymes, and 

 by many it is looked upon as related to them, but the changes it pro- 

 duces do not resemble those produced by proteolj'tic enzymes in all 

 details.^* In particular, complement seems to participate in reactions 

 according to the law of definite proportions, unlike the enzymes. ^^ In 

 certain immune reactions, colloids (lecithin, silicic acid)-" can play the 

 role of complement and immune body, but these reactions are pro- 

 bably quite different from those of bacteriolysis by immune serum. 



Structure of Complement. — According to the Ehrlich theory, complement, 

 like toxins and enzymes, possesses at least two groups: one, the haptophore, by 



11 Noguchi, Biochem. Zeit., 1907 (6), 172. 



12 Courmont et al, C. R. Soc. Biol., 1913 (74), 1152. 

 " Jour. Infect. Dis., 1917 (20), 185. 



1^ Michaelis and Skwirsky, Zeit. Immunitat,. 1910 (7), 497. 



lii Noguchi and Bronfenbrenner, Jour. Exp. Med., 1910 (13), 229; Ritz, Zeit. 

 Immunitiit., 1912 (15), 145. 



i» See Schmidt, Arch. f. Hyg., 1912 (70), 284; Jour. Ilyg., 1914 (14), 437. 



1^ Zoit. Immunitiit., 1913 (16), 503. 



" The curve of complement action resembles that of enzyme action. (Thicle 

 and Emblcton, Jour. Path, and Bact., 1915 (19), 372.) 



i» See Liebermann, Dcut. med. Woch., 190(5 (32), 249. 



20 Landsteinor and Jagic, Wien. klin. Woch., 1904 (17), 03; Munch, med. 

 Woch., 1901 (51), 1185. 



