8 



Scientific Proceedings (25). 



4 (260) 



The hypersensitiveness of the guinea pig to horse serum. 



By PAUL A. LEWIS. 



\_From the Antitoxin Laboratory of the Massachusetts State 

 Board of Health, Boston.'] 



The facts in this communication are related to the "Theobald 

 Smith Phenomenon" first described by Otto. Additional obser- 

 vations in regard to the reaction and its pathology have been 

 reported by Rosenau and Anderson, Besredka and Steinhardt, 

 and Gay and Southard. 



If a normal guinea pig be treated with a dose of 1/100 c.c. of 

 normal horse serum alone, or of diphtheria antitoxic horse serum 

 mixed with a suitable amount of diphtheria toxin, it becomes, 

 after an interval of ten or twenty days, very susceptible to further 

 treatment with normal horse serum. For a guinea pig whose 

 preliminary treatment has been a toxin-antitoxin mixture, after an 

 interval of three weeks, 5 c.c. of serum subcutaneously adminis- 

 tered will frequently kill and will always develop symptoms. 

 Five c.c. intraperitoneally is an almost certainly fatal dose. One 

 one-hundredth c.c. given directly into the circulation is probably a 

 certainly fatal dose. 



As a sensitizing treatment I have employed chiefly the toxin- 

 antitoxin mixture. As a test treatment I have administered the 

 serum subcutaneously as a rule, but have occasionally injected 

 serum into the circulation by the intracardiac method. Two c.c. 

 is a safe dose for a normal animal by the latter method. 



The results of other observers show that diphtheria toxin in 

 some way increases the sensitizing power of the single small dose 

 of serum. With serum alone the same effect can be produced by 

 injecting fractions of the total small dose over a period of several 

 days. In order to show the influence of the toxin, the intra- 

 peritoneal, intracerebral, and intracirculatory methods of testing 

 must be avoided as the more vigorous reaction obtained when 

 they are used masks the result. By injecting 2 c.c. of serum, 

 intracardiac, into animals sensitized by toxin-antitoxin mixtures I 

 have obtained a definite reaction on the sixth day. Careful 



