564 IMMUNOLOGY 



Is not surprising that human serum containing reagin will not 

 passively sensitize the skin of every human or the tissues of the 

 lower animals. 



The apparent inaetivation of reagin when heated to 56° C. for 

 thirty minutes is not in itself a sufficient reason for omitting 

 reagins from the list of true antibodies. Nuttall states that bac- 

 terial precipitins are inactivated at 58-60° C, whereas other 

 immune precipitins are inactivated at 68-70° C. Sherman found 

 that the apparent destruction of heterohemolysin which occurs 

 frequently when serum containing it is heated to 56° C. for thirty 

 minutes is only an interference or masking phenomenon. When 

 the hemolysin is absorbed at 0° C. from the heated serum, it is 

 found to be uninjured. At the present time Coca is inclined to 

 agree with Zinsser that reagins may be regarded as antibodies. 



Antibody Responsible for Immunity. — According to Loveless 

 (1940) the antibody responsible for immunity to hay fever is more 

 thermostable than reagin and unites with its homologous antigen. 

 If the results obtained by Loveless meet with confirmation, a defi- 

 nite advance in our knowledge of hay fever will have been achieved. 



In order to present more clearly certain additional facts about 

 human hypersensitiveness, a few of the clinical allergies will be 

 discussed briefly. For a more comprehensive treatment of the 

 subject the student is referred to the monographs of Duke (1925), 

 Alexander (1928), Coca, Walzer and Thommen (1931), Racke- 

 mann (1931), Zinsser, Enders and Fothergill (1939), Bray (1934), 

 Vaughan (1939). 



Definition of Hay Fever. — Hay fever is a term that is used 

 quite frequently to designate all forms of vasomotor rhinitis, al- 

 though Rackemann prefers to apply it only to vasomotor rhinitis 

 caused by pollen. It will be used in this chapter in the latter sense. 



Attacks of pollen hay fever are seasonal and occur only when 

 an adequate concentration of the plant pollen to which the in- 

 dividual is sensitive is present in the air. The symptoms develop 

 when the pollen comes in contact with the mucous membrane of the 

 nose or with the conjunctiva. Since the dates of pollination of 

 plants in most districts of the United States have been determined 

 by botanists and specialists in allergy and are a matter of record, 

 it is obvioiLS that the history of the date of onset and duration of 

 an attack of hay fever is of material value in determining the par- 



