66 IMMUNITY 



Acquired Anaphylaxis, depending upon 



(a) An attack of disease, erysipelas, diphtheria. 



(b) The injection of dead cells, tuberculin. 



(c) Injection of nitrogenous matter, blood serum and egg- 

 white. 



Direct practical application of theoretical speculation about 

 hypersensitivity may be made in explaining, treating and prevent- 

 ing certain states in man. Mention has already been made of the 

 possibility of intoxicating persons susceptible to the presence of 

 horses by the injecting of horse serum. The only treatment for 

 such a "Schock" is an injection of epinephrin or atropin. 



Serum sickness is explained as a digestion of foreign serum still in 

 the body as such when sufficient ferment has accumulated to 

 digest it, a peroid of three to twelve days. Whether this be cor- 

 rect or not, symptoms can be made milder or prevented by dividing 

 the doses by some hours. A state of hypersensitivity or allergic 

 may also exist to pollen of plants, certain foods and drugs, dusts 

 of feathers and hair or dandruff from cats and dogs. The evi- j 

 dences of this state take the form of asthma, gastrointestinal dis- ' 

 turbances, and skin eruptions of which urticaria and eczema are i 

 the commonest. Detection of this hypersensitivity may be sub- | 

 jective at times but usually it has to be established by technical 

 means. It so happens that allergic persons have either a definite 

 anti-body reaction or the local sessile receptors in the cutaneous 

 cells are stimulated, for the application of the responsible protein 

 to an abraded area on the skin will produce at the point a swollen 

 red areola. In the cases of infection of a bacterial or toxic mix- 

 ture this reaction usually requires twenty-four hours to develop, 

 a delay suggesting that anti-bodies are involved. In the case of 

 serum or pollen allergic, the reaction is almost immediate, suggest- 

 ing local cellular preparation. This is the basis of skin tests, 

 except with tuberculin and the S chick test. Prevention of such 

 allergic poisonings is best accomplished by the avoidance of 



