ioo6 ATOPY 



symptoms have appeared in 72 per cent of the atopic offspring under a bilateral 

 hereditary influence; in 35 per cent of those subject to a unilateral influence, and in 

 only 20 per cent of those with a negative family history; also by noting that all of 

 those subject to bilateral inheritance have shown atopic symptoms by the fortieth 

 year, whereas in the other two groups, the age of onset may be much later — as late 

 as the seventieth year. 



It will be shown presently that this clearly demonstrated hereditary control of 

 the age of onset includes the simple corollary that the age of onset in each atopic in- 

 dividual is determined by heredity. 



ATOPIC REAGINS 



In the blood of nearly all atopic persons that exhibit a positive cutaneous reaction 

 to the known excitant, specific bodies (atopic reagins) can be found which are capable 

 of sensitizing the human skin (Prausnitz and Kiistner,' De Besche,^ and others). 



So far as the writer is aware, no means is available for the demonstration of the 

 atopic reagins other than their specific property of sensitizing the human skin. In 

 mixtures of the reagins with the related atopen, no precipitation has been observed 

 nor fixation of complement. Indeed, it seems that the reagins lack even the most 

 characteristic property of antibodies prepared against soluble antigens — the property 

 of rendering the respective antigen specifically inactive.^ Thus, antitoxin specifically 

 extinguishes the toxicity and binding power of the related toxin and anaphylactic 

 antibody specifically inhibits the shock-producing property of its related antigen. 

 But atopic reagin seems completely to lack the power to prevent the related atopen 

 from causing its typical reaction in a sensitive human skin. 



Coca and Grove" were unable to sensitize the normal human skin with an anti-egg 

 precipitating and sensitizing serum from a rabbit; these wholly negative results have 

 since been confirmed separately by Grove and by the writer, and also in a series of 

 independent experiments by Walzer.^ Walzer did obtain some reactions when the in- 

 jected skin sites were tested within twenty-four hours (less after forty-eight hours) ; 

 but these were shown to be non-specific, since identical reactions could be obtained 

 with an unrelated antigen (cottonseed extracts). Walzer'' has also reported complete 

 failure to sensitize the human skin with an unusually high-titred anti-egg serum from 

 the rabbit, when he tested the injected site by his method of intestinal absorption. 



There are some reports of successful passive sensitization of the guinea pig with 

 the serum of idiosyncratic human beings.^ These experiments were carried out at a 

 time when the atopic reagins were not known. The more recent experiments of this 

 kind have resulted negatively. Particularly significant are those of Spain, who selected 

 the sera of persons that were atopically sensitive to typical anaphylactogens and who 



' Prausnitz, L., and Kiistner, H.: Cenlralbl.f. Bakteriol., Orig., 86, 160. 1921. 



2 de Besche, A.: Am. J. M. Sc, 166, 265. 1923. 



^Levine, Philip, and Coca, A. F.: /. Immunol., 11, 411. 1926. 



■• Coca, A. F., and Grove, E. F.: ibid., 10, 445. 1925. 



5 Walzer, M.: personal communication. 



^Walzer, M.: J. Immunol., 14, 159. 1927. 



7 Bruck, C: Arch.f. Dermal, u. Syph., 96, 241. 1909. 



