Rate of Complement Fixation. 



139 



83 (1261) 



The effect of temperature on the rate of complement fixation. 



By J. Bronfenbrenner and M. J. Schlesinger. 



[From the Research Laboratories of the Western Pennsylvania 

 Hospital, Pittsburgh, Pa.] 



Suitable temperature is one of the most important prerequisites 

 to the proper progress of biological reactions. Since the com- 

 plement fixation reaction is used so widely at present and the 

 relation between the temperature and rate of fixation has not been 

 studied systematically thus far, we thought it advisable to study 

 this question. This was especially necessary, since many authors 

 have varied the technique of the routine complement fixation 

 test in this respect. The practical points brought out in this 

 study are as follows: 



1. If a rapid fixation of complement is desired we found that 

 a temperature of 37 0 C. is the best. For diagnosis one-half-hour 

 incubation at this temperature is the most efficient. We found, 

 however, that, if sufficient antibody is present in the serum (3-5 

 units or more), fixation of two units of complement already takes 

 place within the first five minutes, provided the amount of antigen 

 used contains several antigenic units. We find it possible to use 

 this procedure for presumptive elimination of strongly positive 

 sera from a large series of cases. One places in a tube 0.05 c.c. 

 of the patient's serum, adds the proper amount of antigen and 

 salt solution and incubates at 37 0 C. in the water bath for five 

 minutes and then adds sensitized cells to test for free complement. 1 



2. If the time element is not so important, but complete 

 fixation of the complement is desired, then we find that incubation 

 in the ice box for 8-10 hours is best. These fixations on ice, 

 however, may not be specific, for the reaction of fixation is so 

 complete under these conditions that even traces of secondary 

 circulating antigens and their corresponding antibodies may cause 



1 One must, of course, test 0.025 c.c. of the serum for complement at the same 

 time, to ascertain that there are at least two units of complement originally present 

 in the amount of serum used in the test. 



