168 CHEMISTRY OF THE IMMUNITY REACTIONS 



sharp reaction that follows intravenous injections of killed typhoid 

 bacilli into typhoid patients has been found to result equally well if 

 colon bacilli are used, or deutero-albumose. One possible explana- 

 tion of this type of reaction is that the injected substance acts as a 

 common antigen, which causes the production of common antibodies 

 that react also with the antigens of the cause of the disease. Another 

 possibility is that the foreign protein stimulates the tissues that 

 form antibodies, presumably the red marrow, so that they produce 

 not only antibodies for this antigen, but also for the antigens of the 

 specific etiologic factor of the cHsease that have been stimulating the 

 bone marrow previously. Hektoen" has observed, for example, that 

 if an animal that has previously produced precipitins for one foreign 

 protein is reinjected with a different protein it will then produce pre- 

 cipitins for both these proteins, and possibly for other proteins with 

 which it has not been injected. ^^ Moreover, the febrile reaction, the 

 ieucocytosis, and other phenomena, such as the antiferment index of 

 the serum (Jobling),^^ that injection of nonspecific protein produces, 

 may be responsible for favorably affecting the disease, rather than 

 actual antibody formation. 



The opposite type of phenomenon, that is, non-specific interference 

 with immunological reaction, is suggested by the observations of J. H. 

 Lewis.'" He found that small quantities of one protein injected into a 

 guinea pig together with or shortly after large quantities of another 

 protein (e. g., egg albumen in dog serum) would not sensitize the 

 animal, although a similar amount injected alone would always sensi- 

 tize. The suggested explanation is that the larger amount of foreign 

 protein combines with so many of the available cell receptors that few 

 of the small number of sensitizing protein molecules are able to be 

 bound to the cells and to stimulate antibody formation; this explana- 

 tion assumes a certain lack of specificity on the part of the cell receptors. 



An interesting illustration of the fact that whatever stimulates the 

 bone marrow may cause it to form, among other blood elements, spe- 

 cific antibodies, is furnished by the behavior of antitoxin-producing 

 horses. If a horse that has been immunized to diphtheria toxin is 

 bled as much as possible, it will be found to have regenerated the lost 

 antitoxin within 48 hours, ^' even although the last immunizing dose 

 of toxin was received long before. Also, it is stated that jiersons who 

 have once had typhoid, but whose blood no longer contains much 

 agglutinin, may show a high typhoid agglutinin content when infected 

 by some other organism, or after any sharji febrile attack. It is 

 highly possible that many therapcnitic agents may similarly act by 



" Jour. Infoc;t. Dis., 1917 (21), 279. 

 «8 See also Ifemiuinii, Udd., 191.S (23), 457. 



*" See review of tliis suhject, llarvev Lectures, 1917 (12), ISl; also Cowie and 

 Calhoun, Anrli. Int. Med., 1919 (2;{), ()9. 

 '» Jour. Infect. Dis., 1915 (17), 211. 

 ^' O'Brien, Jour. Path, and Bact., 1913 (18), 89. 



