288 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



in question (immunity), has called forth a general, increased suscep- 

 tibility to the action of its products of disintegration (anaphylaxis) . 

 According to v. Pirquet this difference in response is readily accounted 

 for, if we remember that the parenteral introduction of foreign pro- 

 teins (in the present instance of bacterial proteins) leads to the 

 formation of corresponding antibodies, and that as a consequence 

 of the interaction between the two groups of substances, in the 

 presence of complement, toxic bodies (anaphylatoxins) are formed 

 which may then produce symptoms of variable nature, according to 

 the character of the tissues which are susceptible to their action. 



In man results have been obtained which are perfectly analogous 

 to those observed in the guinea-pig. The subcutaneous injection 

 of the non-tubercular individual with small doses of tuberculin will 

 thus produce no deleterious consequences whatever, while in the 

 tubercular subject the same dose causes the well-known general 

 response by headache, muscle pains, and fever, besides the local 

 inflammatory reaction at the site of the injection. In cases where 

 the tubercular lesion is superficially located and can be directly 

 observed the development of increased redness and swelling, more- 

 over, give evidence of a direct effect upon the seat of infection. 

 The same is shown by the increase in the number of the rales 

 and in the number of bacilli in the sputum, if the injection is 

 given in a case of pulmonary tuberculosis (focal reactions). 



If, on the other hand, the tuberculin is administered in such a 

 manner that active resorption does not occur, local reactions only 

 will be observed, and in tissues, it should be remembered, which 

 are not tubercular in themselves. Following a cutaneous inoculation 

 with tuberculin an inflammatory papule thus appears, no matter 

 at what point the injection is made (v. Pirquet reaction), instillation 

 into the conjunctival sac gives rise to an intense conjunctivitis 

 (Calmette reaction); inunction with a tubercular salve calls forth a 

 local dermatitis (Moro reaction), etc. 



Owing to this remarkable hypersusceptibility to tuberculin on 

 the part of the tubercular subject, the principle in question has been 

 extensively utilized for diagnostic purposes, and it may not be out 

 of place to briefly describe the most important methods which 

 have been advocated for this purpose. 



The Tuberculin Test According to Koch (subcutaneous method). 

 The material which is employed to this end is the old tuberculin of 



