HYPERSUSCEPTIBILI TY 369 



many ways to the toxin skin reactions as observed in the Schick 

 test with diphtheria toxin. The relationships of these latter reac- 

 tions to anaphylaxis has been much questioned and with justice. 

 A recent analysis by ourselves in the case of the tuberculin reaction 

 has shown that these reactions are not anaphylactic in the ordinary 

 sense, but are brought about by substances probably proteose in 

 nature which among other things, differ from the true anaphylactic 

 antigens in being more permeable than these, and penetrating into 

 cells. We refer the reader to our article in the J. of Exp. Med., 

 unpublished, probably 1921. 



METHODS OF TESTING AND DESENSITIZATION IN INDIVIDUALS ABOUT 

 TO BE INJECTED WITH ANTITOXIC OR ANTIBACTERIAL SERA. A consider- 

 able degree of practical importance attaches to the anaphylactic 

 phenomena in connection with the administration of sera. When 

 small doses of tetanus or diphtheria antitoxin are to be administered 

 for the first time, it is generally unnecessary to precede this with 

 a skin test. Although we should always advise that this is done 

 in asthmatics or in people who have suffered from chronic coughs 

 or the prolonged pulmonary inflammations that are apt to occur in 

 children following measles, influenza or whooping cough. This is 

 necessary for the reasons stated above and pointed out by Huber 

 and Koessler, which demonstrated the hypertrophy of smooth 

 muscles in the bronchioles of such people. 



When intravenous serum injections are to be made, as in the 

 treatment of pneumonia and meningitis, it is best to precede the 

 injection with a skin test. Such tests have been done more fre- 

 quently than anywhere else, we believe, at the Rockefeller Hospital, 

 where 0.02 c.c. of a 1 :10 dilution of horse serum is injected intra- 

 cutaneously with a similar injetcion of sterile salt solution as control. 

 In unsensitive people the wheal of the injection disappears rapidly. 

 But in sensitive ones it will begin to increase after five or ten 

 minutes, and within four hours may show a large red erythematous, 

 urticaria-like area. 



In such cases, careful desensitization should be practiced. The 

 precautions to be taken are twofold. One consists of a preliminary 

 attempt at desensitization, the other in slow administration by dilu- 

 tion of the serum during the injection of the therapeutic dose. 



The desensitization is best accomplished by the method of 

 Besredka 54 which consists in the gradual injection of progressively 



64 Besredka, Bull, de 1 'Inst. Past., 6, 1908, 826. 



