CHAPTER IX 

 HEMOLYSIS AND SERUM CYTOTOXINS 



CYTOTOXINS 



JUST as precipitins can be obtained for proteids derived from 

 other sources than bacterial cells, so also upon immunizing an ani- 

 mal against various types of cells other than bacteria, substances 

 appear in its serum that exercise a destructive effect upon the 

 type of cells injected. In other words, the reactions of animals 

 to infection are not specially devised for combating bacteria 

 and their products, but can be equally exerted against non- 

 bacterial cells and their products. It may be stated as a 

 general law that a certain degree of immunity, accompanied by 

 the appearance of specific "antibodies" in the serum, may be 

 obtained by injecting any sort of foreign cell or proteid sub- 

 stance into an animal ; but that such immunity cannot be 

 obtained unless the injected material is of a proteid nature or 

 very closely related to the proteids, e. g., enzymes and toxins. 

 In the case of soluble proteids, as before mentioned, the anti- 

 bodies show their effects by precipitating them, with agglutina- 

 tion of the particles into flocculi ; in the case of cells, whether 

 bacterial or tissue cells, the antibodies cause agglutination and 

 loss or impairment of vitality. This injury may be manifested 

 by loss of motion in motile cells (bacteria, spermatozoa, ciliated 

 epithelium) or by solution of their contents (bacteriolysis, 

 erythrocytolysis, leucocytolysis, etc.), or by cell death without 

 marked morphological alterations (B. typhosus, spermatozoa). 

 If we inject red corpuscles, leucocytes, spermatozoa, renal epi- 

 thelium, or any other foreign cell, the reaction is, therefore, as 

 specific as it is if we inject bacteria, and of exactly the same 

 nature. Therefore, all that has been said previously concerning 

 bactericidal substances and agglutinins can be transposed to 

 apply to immunity against tissue cells. As a matter of fact, 

 however, the transposition is generally made in the other direc- 

 tion, for red corpuscles are much easier cells to study than bac- 

 teria, because their laking gives prompt and readily recognized 

 evidence that the toxic serum has brought about changes. 

 Much of our knowledge of bactericidal serum has been obtained 

 through studies of the mechanism of erythrocytolysis, the results 



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