236 THE PRINCIPLES OF IMMUNOLOGY 



crusts. In unusually sensitive individuals the local reaction may be 

 accompanied by systemic manifestations. Less severe but sometimes 

 confusing reactions may appear in the form of pseudo-reactions 

 which are non-specific in nature and probably due to the 

 action of body proteases upon introduced proteins. The reaction 

 to the traumatism from the introduction of the protein may at times 

 be somewhat confusing but in most instances is slight. Certain drugs, 

 such as iodides and bromides, appear to increase the intensity of reac- 

 tions whether they be specific or non-specific. Iodides are known to 

 reduce the antiferment titer of the blood, and it is possible that the 

 use of these drugs therefore liberates protease and in this way acceler- 

 ates the non-specific local reaction. The increase of the specific local 

 reactions is probably due to the increase of the non-specific interaction 

 of protease and the introduced protein. 



Theories of Cutaneous Reactions. The appearance of local reac- 

 tions in hypersusceptibility may be explained according to any of the 

 theories offered for anaphylactic shock. If the mechanism of ana- 

 phylaxis involves the formation of poisons these may be concentrated 

 in situ because of the irritation produced by introducing the antigen. 

 The irritation leads to a slight local inflammation with its incident vaso- 

 dilatation and edema. Thus there is a local concentration of antibody, 

 which in reaction with the introduced antigen produces a hypothetical 

 poisonous substance. If the sensitizing substance is within cells, the 

 local contact of antigen in the tissues of the skin explains the local 

 reaction. Similarly the physical theories are adaptable. Stokes, for 

 example, has found that agar will produce a local non-specific reaction. 

 This is probably the result in part of a local loss of balance between 

 ferment and antiferment due to adsorption of the latter by the agar. 

 Similarly any of the physical theories might apply, but the acceptance of 

 the importance of the cells in the reaction, whether physical or other- 

 wise, offers an excellent reason for the early appearance and severity 

 of the local reaction without general manifestations. Cooke, Flood and 

 Coca state that antibodies are not demonstrable in the blood of naturally 

 sensitive persons and therefore emphasize the essential importance of 

 the cells. While agreeing that the cells play a most important part, 

 the experiments of Koessler and the case reported by Ramirez suggest 

 that natural sensitization is of essentially the same nature as anaphylaxis, 

 with marked differences only in the degree of cellular and humoral 

 participation. Therapeutic desensitization of man lasts for a relatively 

 short period of time and differs only in duration from desensitization 

 in experimental animals. In both cases the phenomenon is specific 

 for the antigen employed. 



Gay and Force, Gay and Claypole, and Gay and Minaker, in their 

 work with cutaneous reactions in typhoid fever and in the carrier state 

 in meningococcus infections, have expressed the opinion that positive 

 reactions are an indication of resistance on the part of the body against 

 infection by the organisms concerned. Nichols studied the typhoidin 

 test (see page 242) in individuals who had survived typhoid fever and 



