CHAPTER XVI 

 CYTOLYSINS, INCLUDING BACTERIOLYSINS, AND HEMOLYSINS 



(Antibodies of Ehrlich's Third Order) 



THE use of animal, plant, or bacterial cells as antigens has been 

 found usually to cause the development, by the tissues, of specific 

 antibodies, which have the power of destroying these cells, and 

 in many cases of actually dissolving or digesting them. These 

 antibodies are termed cytotoxins. In most cases the action is 

 lytic or dissolving; the antibodies are cytolysins. Cytolysins are 

 frequently subdivided with reference to their antigens, as bac- 

 teriolysins, hemolysins, nephrolysins, etc. Any substance which 

 destroys bacterial cells is said to be bactericidal, and this expression 

 is used when the method of cell destruction is not specified. Cyto- 

 lysins are produced by certain bacteria, and are also found in 

 certain snake venoms. 



Bacteriolysins were first noted by Pfeiffer. He found that 

 when cholera spirilla were injected into the peritoneal cavity of the 

 immune guinea-pig, the serous exudate rapidly dissolved and 

 destroyed them. This lytic action of the blood-serum is called 

 Pfeiffer's phenomenon. Later, it was discovered that this reaction 

 would take place just as well in a test-tube (in vitro) as in the 

 animal body. 



Cytolysins. Cytolysins have been shown to be made up of two 

 elements. When a cytolytic serum is heated to 56 for half an 

 hour, or is allowed to stand for a time, it loses its lytic property. 

 This is regained, however, when a little fresh normal serum is added. 

 The normal serum is said to reactivate the immune serum. The 

 normal serum alone is not lytic, nor is the immune serum, but when 

 mixed, they will destroy cells. It is evident, therefore, that the 

 cytolysin is made up of two constituents, neither of which can 

 act without the other. The thermostabile constituent of the im- 



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