CHAPTER XXVII 



THE SIGNIFICANCE OF ALLERGY IN 



TUBERCULOSIS AND A FEW OTHER 



DISEASES 



Immunity in Tuberculosis. — As a result of extensive investiga- 

 tion it has been definitely established that the resistance of sus- 

 ceptible animals such as man, rabbits, guinea pigs, etc., to infec- 

 tion with the tubercle bacillus can be increased by infection with 

 either virulent or avirulent human or bovine strains and also to 

 a moderate extent by the injection of a suspension of killed 

 tubercle bacilli. 



Numerous anatomical studies of primary and reinfection types 

 of tuberculosis offer abundant evidence that partial immunity 

 results from infection with the tubercle bacillus. The primary 

 or childhood tj^pe of tuberculosis occurs when the organisms 

 lodge in a body that is neither allergic nor immune. In primary 

 pulmonary tuberculosis the original lesion may be anywhere in 

 the lung, no allergic symptoms are detectable and the regional 

 lymph glands soon become involved. In the reinfection or so- 

 called adult type of pulmonary tuberculosis the lesion is as a rule 

 in the apex of one or both lungs, allergic symptoms may develop 

 and the regional lymph glands are not involved because the 

 tissue immunity, due to the first infection, localizes the organisms 

 and limits the pathway of spread largely to the bronchi. For a 

 more comprehensive discussion of the occurrence and significance 

 of the various lype,s of tuberculosis the student is referred to 

 papers by McPhedran and Opie (1933), McPhedran (1933), 

 Hetherington (1933) and Opie (1933). At the present time there 

 is some controversy over the mechanisms involved and the role 

 which allergy plays in acquired immunity to the tubercle bacillus. 

 Krause (1910, 1916) made an extensive study of tuberculin allergy 

 and immunity and suggested that tissue hypersensitiveness may 

 play an important role in immunity. 



It will be recalled that in Chapter VII the mechanism of ac- 

 quired resistance to infection is discussed. According to Cannon, 



538 



