Abstract
Suitable temperature is one of the most important prerequisites to the proper progress of biological reactions. Since the complement 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° 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° 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 fixation of complement. 1 The ice-box fixation can therefore be used only as a presumptive test to eliminate the negative cases. 2
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