568 IMMUNOLOGY 



other members of the same group. Many instances of the disap- 

 pearance of food allergy are on record. 



The value of the botanical classification of plants yielding com- 

 mon food allergies suggested by Vaughan (1930) and Ellis (1931) 

 as a basis for carrying out food testing is definitely questioned by 

 Piness, Miller, Carnahan, Altose and Hawes (1940). In their 

 opinion a botanical classification is an unreliable guide to pre- 

 dicting skin reactivity to a food when reactivity to a botanieally 

 related food is known. 



Drug" Allergy. — Reports of cases of hypersensitiveness to one or 

 more of the medicinal drugs are quite numerous in the literature. 

 As a rule the principal symptom is some form of an eruption. 

 The latter is usually accompanied by itching. Occasionally there 

 are dyspnea, edema, swelling of the joints and of the lymph nodes. 

 The symptoms appear, in most cases, within a few hours after the 

 drug has been administered. Antibodies are not demonstrable. 

 When hypersensitiveness is once established, the patient as a rule 

 remains sensitive for life. The development of temporary tolerance 

 to quinine in an individual hypersensitive to quinine is reported by 

 Heran and St. Girons (1917). Loveman (1939) lias given an 

 excellent brief discussion of allergic drug eruptions. 



Landsteiner and his associates (1935, 1936, 1938, 1940) report 

 experimental results indicating that certain simple chemical sub- 

 stances may function as haptens and unite with the body protein 

 to form new antigens, giving rise to symptoms of drug allergy or 

 contact dermatitis, depending upon conditions. 



Contact Dermatitis. — In contact dermatitis the shock organ 

 is the epidermis. The lesions develop in the allergic individual 

 from surface contact with the exciting agent but do not result 

 from the injection or ingestion of the latter. The results of exten- 

 sive statistical studies indicate that a Mendelian factor is not in- 

 volved in this type of human idiosyncrasy. Contact dermatitis 

 was regarded formerly as due to the action of plant poisons upon 

 the skin and for this reason the nomenclature of dermatitis due 

 to exciting agents in poison ivy, poison oak, etc., is misleading, 

 since the dermatitis is a manifestation of specific hypersensitive- 

 ness to a nonantigenic excitant which is quite often soluble in fat 

 solvents and is not due to a specific toxin. 



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