IOI4 ATOPY 



it could be found in lower animals. However, there have been some efforts to induce 

 in the guinea pig symptoms that are similar to those of asthma and hay fever, under 

 conditions of contact like those that obtain in these two atopic states. 



Guinea pigs that have been made to breathe air in which pollen was suspended 

 have been thought to exhibit signs of hay fever ("sneezing" and lacrimation, without 

 asthma) after a. certain period of exposure.^ 



These experiments, which have not been repeated, must be viewed in the light of 

 the general experience that guinea pigs sensitized with pollen extracts exhibit, upon 

 any mode of testing, symptoms and pathology that are the same as those induced 

 with the usual protein antigens. In other words, the shock organ is always the same 

 in the guinea pig; and it remains the same whether the antigen is administered by in- 

 jection, by ingestion, or by inhalation. The lacrimation that one occasionally sees in 

 the guinea pig in anaphylactic shock has been likened to hay fever ;^ but hay fever is 

 more than a lacrimation. 



The bronchospasm of anaphylactic shock in the guinea pig has generally been 

 considered identical in its mechanism with the asthmatic attack, and, in guinea pigs 

 sensitized to horse dander, the bronchospasm has been induced by causing the sensi- 

 tive animal to breathe the antigen in a spray. This mode of administration of the an- 

 tigen was used in imitation of the natural mode of contact with the excitant in asth- 

 ma. However, it has been found that, under these conditions, the antigen always 

 reached the bronchial shock organ of the guinea pig through the bloodstream, after 

 being absorbed through the respiratory mucous membrane, exactly as if it had been in- 

 jected. This could be seen in the fact that, when shock was induced in the sensitive 

 guinea pigs with the inhaled antigen, the uterine muscle was found always to be de- 

 sensitized. When no shock occurred, the uterus remained sensitive.^ 



More recently an effort has been made to bridge the gap between idiosyncrasy and 

 anaphylaxis by the experimental production of a dermatitis in guinea pigs with nickel 

 salts. 4 This experiment was suggested by the occurrence of an itching eruption in a 

 considerable percentage of human beings working with nickel. It seems necessary to 

 call attention to the lack of demonstrated connection between atopic hypersensitive- 

 ness and the nickel dermatitis. If those that oppose the separation of the hypersen- 

 sitiveness of atopy from that of anaphylaxis are merely seeking a form of hypersensi- 

 tiveness that occurs in both human beings and in lower animals, they can most easily 

 find it in the hypersensitiveness of infection (tuberculin-mallein type), which is typi- 

 cally exhibited by the surface membranes. One need not deny the possibility that 

 other forms of hypersensitiveness besides this one affect lower animals as well as 

 human beings, and of all tissues the skin seems most likely to show such common 

 susceptibility. But, if other susceptibilities should be found that are common to man 

 and the lower animals, this will not necessarily remove the many theoretical as well 

 as practically important differences between atopy and anaphylaxis. However, a 

 further study of the nickel dermatitis in guinea pigs would be welcome. E. L. Milford 



' Ulrich, Henry L.: /. Immunol., 3r4S3- 1918. 



' Doerr, R.: Weichardt's Ergehn. d. Uyg., 5, 73. 1922. 



3 Alexander, H. L., Becke, W. G., and Holmes, J. A.: J. Immunol., 11, 175. 1926. 



■• Waltluvrd, B.: Sclrweb. med. Wchnschr., 56, 603. 1926; Abstract, J .A.M .A., 87, 709. 1927. 



