LIPOIDS AS ANTIGENS 163 



with antibodies for tubercle bacilli,^* and much more effectively than the protein 

 residue of the bacilli, wherefore he concludes that the reactions obtained with 

 the lipoids certainly cannot be ascribed to adherent traces of protein. BergeP" 

 observed after lecithin injections in rabbits, not only an increase in the lipase con- 

 tent of the blood and tissues, but also the presence of complement-binding anti- 

 bodies, and Jobling and Bull" have found an increase in serum lipase after 

 immunizing with red corpuscles.'* 



The number of reputed positive results with lipoids makes it impossible at this 

 time to state dogmatically that lipoids may not possess antigenic properties, but 

 it must be taken into account that the successful use of lipoids as antigens in comple- 

 ment fi.xation reactions is not proof of their true antigenic nature, in view of our 

 present lack of knowledge of the actual nature of this reaction itself. MacLean,'' 

 indeed, found evidence that even in the Wa-ssermann reaction the active substance 

 is not lecithin itself, but some other unknown substance which could be obtained 

 practically lecithin-free. Furthermore, we have the testimony of Fitzgerald 

 and Leathes^'* that a lipoidal material from liver, which was itself capable of serving 

 as antigen in the Wassermann reaction, did not engender complement-fixing 

 antibodies in rabbits immunized with this lipoid. Ritchie and Miller" could find 

 no antigenic activity in the lipoids of serum or corpuscles. Also Kleinschmidt,'® 

 who accepts the antigenic nature of nastin, was unable to secure antibodies by 

 immunizing rabbits with it. Thiele" says that as lipoids possess no specificity 

 they cannot give rise to antibodies. Neufeld found that rabbits immunized with 

 lecithin developed no opsonins for lecithin emulsions. A suggestive observation is 

 that of Pick and Schwarz,'* who found that the presence of lecithin increases the 

 antigenic power of bacteria, which may help to explain the activity of possible traces 

 of proteins in lipoid preparations used as antigens. 



Simple Chemical Antigens. — Many drugs cause a hypersensitization, and in 

 this respect seem to behave as antigens producing anaphylactic antibodies. It 

 happens that most of these chemicals are of such a nature as to permit of their 

 union with proteins, and it seems probable that such protein compounds behave 

 as foreign proteins to the animal in which they are formed, for it has been found 

 that guinea-pig serum treated with iodin can render guinea-pigs sensitive to the 

 same iodized serum. '^ Hence, hypersensitiveness to iodin compounds would be a 

 reaction to iodized proteins,'*" and not to the non-protein iodin compound; the 

 same applies to anaphylactic reactions observed with salvarsan, atoxyl.^i copper 

 compounds,** and perhaps aspirin and antipyrin.*' Zieler, however, has ques- 

 tioned the validity of many of the experiments on which these views are based. ■•* 

 It is possible that certain chemicals may react in such a way with the tissue or blood 

 proteins as to make them sensitive to the animal's own complement, which then 



2^J*w^a912 (14), 359; 1912 (15), 245. 



30 mxit. .\rch. klin. Med., 1912 (106), 47. 



'1 Jour. Exp. Med., 1912 (16), 488. 



'* Bogomolez suggests that the lipoids themselves may be produced in excess 

 for defense against various poisons, which they serve to inhibit, especiallj- the 

 toxin of /i. hotulinus. (Zeit. Immunitat., 1910 (8), 35). 



'* Lecithin and Allied Substances, Biochemical Monographs, 1918, p. 170. 



^^ Univ. of Calif. Publ., 1912 (2), 39. 



" Jour. Path, and Bact., 1913 (17), 429; but Wang. {Ibid., 1919 (22), 224) 

 obtained positive results with ether-chloroform extracts of corpuscles. 



'« Berl. klin. Woch., 1910 (47), 57. 



"Zeit. Immunitat., 1913 (16), 160. 



38 Biochem. Zeit., 1909 (15), 453. 



39 Friedberger and Ito, Zeit. Immunitat., 1912 (12), 241. 



*" According to Block (Zeit. exp. Path., 1911 (9), 509) iodoform idiosyncrasy 

 depends upon the CH3 rather than on the iodin, and is a local cellular reaction 

 rather than a humoral reaction, the protoplasm having an increased affinity for 

 methyl radicals. (See Weil, Zeit. Chemotherapie, 1913 (1), 412.) 



*^ Moro and Stheeman, Miinch. med. Woch., 1909 (56), 1414. 



^- Hollande, Compt. Kend. Soc. Biol., 1918 (81), 58. 



" Bruck, Berl. klin. Woch., 1910 (47), 1928; Klausner, Munch, med. Woch., 

 1911 (58), 138. 



" Miinch. med. Woch., 1912 (59), 401. 



