COMPLEMENT 165 



This union at low tem])eratures makes possible a primary incuba- 

 tion of 6° to 8° C. in complement fixation work. 



Effect of Temperature on Complement Action. — In regard to 

 the effect of temperature upon complement action, Zinsser says the 

 si)eed and i'ompleteness of the union of complement and sensitized 

 antigen increase as the temperature approaches 40° C. 



Discussion of Eagle's Work.— Eagle (1929) has reported a 

 scries of experiments attempting to explain the mechanism of com- 

 plement fixation. He finds, as others before him, that qualitatively 

 speaking, tlie plienomenon of hemolysis appears to represent a 

 inonomolccular reaction, and that shortly after hemolysis appears, 

 there is an inci-ease in the rate of fixation of complement. He 

 studied and compared fixation of complement by agglutinated bac- 

 teria, immune precipitates and sensitized red cells, and noted a 

 similarity in the curves, with the exception of this added fixation in 

 the case of hemolysis. Liefmann and Cohn (1911) noted this, as 

 did Thiele and Embleton (1914). While it is an interesting 

 observation, it does not prove the monomolecular nature of the 

 reaction, nor is it so regarded by Eagle. He concludes that ''the 

 physical constants of fixation (temperature coefficient, velocity, 

 quantitative relationships between the reactants) are those com- 

 monly associated with adsorption processes and are the same in the 

 three types of fixation studies. " 



While this is a good working explanation of complement fixa- 

 tion, it should be remembered that his conclusions result largely 

 ])ecause his data fit Freundlich's equation for adsorption processes 

 and also because the figures he obtains for temperature coefficients 

 are low as is the case in adsorption reactions. The Freundlich 

 equation is usually used in the sense of circumstantial evidence 

 rather than proof, and the problem is such that it is doubtful 

 whether the temperature coefficients he reports are significant. 

 Since this explanation of complement action is perhaps the most 

 commonly accepted one, it can be used as a working hypothesis 

 for the present. This admits that both chemical and physical fac- 

 tors are involved, and assumes that complement is bound to the 

 antigen-antibody complex preliminary to any lytic action that may 

 occur, and also admits of the interference of lysis by secondary 

 products liberated or formed in the process. 



