228 WARFIELD T. LONGCOPE AND GEORGE M. MACKENZIE 



disease. The facts, however, do not appear to warrant such a sweeping 

 conclusion and it would seem more in accordance with experimental evi- 

 dence to consider serum disease and the various results of the artificial 

 introduction of native proteins parenterally into the human being as 

 following the same principles that govern the reactions in the anaphy- 

 lactic animal. This was the conception which was originally held by 

 von Pirquet and Schick and which has been emphasized by Longcope 

 and Rackemann and by Mackenzie and Leake. 



When one considers the relative susceptibility of different species to 

 sensitization by foreign proteins, it is found that this varies considerably. 

 The guinea-pig represents the animal which is most susceptible to sensi- 

 tization by foreign proteins. The dog and the cat come somewhat lower 

 in the scale and it is well known that it is considerably more difficult to 

 sensitize the rabbit than perhaps any of these animals. Previously, it was 

 thought that the lower monkeys could not be made anaphylactic towards 

 horse serum but recently it has been shown by Zinsser that the Macacus 

 rhesus and the Cebus monkey may be made anaphylactic, both to horse 

 serum and to egg white, though sensitization is attained with some diffi- 

 culty and, as indicated by tests made with the Dale method, of uterine 

 muscle strips, is only of moderate intensity. The susceptibility to arti- 

 ficial sensitization places the human being in this scale apparently above 

 the monkey. 



It seems desirable, therefore, to consider serum disease and the effect 

 that follows artificial sensitization in man as analogous to anaphylaxis in 

 the experimental animal and to separate into a second class the spon- 

 taneously or naturally hypersensitive individuals, the relation of which 

 to experimental auaphylaxis is not clear and the fundamental principles 

 of which need considerable- investigation and study irrespective of the 

 relationship of this condition to experimental anaphylaxis. 



Though the diseases associated with spontaneous sensitization such 

 as hay fever, asthma, eczema, urticaria and the acute gastro-intestinal 

 disturbances of both infants and adults, have of themselves been familiar 

 for many years and though great numbers of these patients now have 

 been subjected to skin tests, to determine whether or not they belong to 

 the group of spontaneously hypersensitive individuals and whether or 

 not the materials to which their skin shows hypersensitiveness is responsi- 

 ble for their symptoms, it is surprising how comparatively few investiga- 

 tions have been made upon the physiological and chemical reactions of 

 this group of patients who are proven to show such idiosyncrasies. Ex- 

 amination of the blood has shown that in asthma there is quite frequently 

 an increase in the eosinophilic leukocytes, but this is by no means a regu- 

 lar finding in the case of individuals with spontaneous hypersensitiveness 

 and perhaps a more constant and a striking feature of this dyscrasia in 

 Adults is the relative increase in the small lymphocytes of the blood. 



