METHODS OF STUDYING CYTOTOXINS 535 



possess the same general properties as the bacteriolysins and hemoly- 

 sins, except that, as will be pointed out later, they do not possess the 

 same specificity. Without the presence of a complement they are 

 inactive. They are thermostabile, possess the same general affinity for 

 their antigen, and may be removed from a serum by saturation with 

 the antigen in a manner similar to that used for the removal of a 

 hemolysin. 



Preparation of Cytotoxins. Cytotoxic serums are prepared by im- 

 munizing an alien animal with fine suspensions of cells of the particular 

 organ being studied. (See p. 73.) Every effort should be made to 

 remove all traces of blood, and to secure as pure an emulsion of the same 

 cells and to work as aseptically as possible. Injections are best given 

 intraperitoneally, rabbits being well adapted for the preparation of 

 these serums. 



Beebe l has made the statement that more specific serums are obtained 

 if the nucleoproteins are isolated and used in the process of immuniza- 

 tion, than if the cells themselves are used. Wells, 2 however, believes 

 that the nucleoproteins of cells are not specific in character, and Pearce, 

 Karsner, and Eisenbrey 3 found that nephrotoxic and hepatoxic serums 

 prepared by the injection of the nucleoproteins of these cells, were no 

 more toxic than serums prepared from the globulins and albumins of the 

 same organs. 



Methods of Studying Cytotoxins. While the phenomena of hemolysis 

 and bacteriolysis may readily be observed in experiments in vitro, the 

 influence of other cytotoxins on the particular cells used as antigens is 

 more difficult to determine. The methods of exposing cell emulsions 

 to the action of the serum have not been found satisfactory for testing 

 the specificity of cytotoxins. 



The technic generally employed consists in making subcutaneous, 

 intraperitoneal, or intravenous injections of the immune serum into the 

 animal, or into the arteries leading to particular organs. Functional dis- 

 turbances and delicate histologic changes in various organs have served as 

 criteria for determining the degree of specificity that exists. The loss of 

 some manifestation of vitality on the part of the cell, as a loss of motility 

 (spermatozoa) or an inability to proliferate, may aid in studying the 

 effect of these serums. 



More recently several other methods have been used, especially the 



1 Jour. Exper. Med., 1905, vii, 733. 



2 Chemical Pathology, 1914, Second Edition, W. B. Saunders Co. 



3 Jour. Exper. Med., 1911, xiv, 44. 



