Presence of Typhus Antibodies in Commercial Frozen and Dried Complement.

Abstract

Frozen and dried complement from commercial sources has been used by this laboratory for the past two years in the performance of the virus and rickettsial 1 , 2 complement fixation tests. With the exception of an occasional ampule giving a low titer due to a poor vacuum or inadequate drying, at no time did we experience any serious difficulties with this material. However, in a recent series of tests, we have had results which can be best explained on the basis of the presence of specific antibodies in the particular product being used.

The initial observations were as follows: In a test containing a large number of human sera being titrated against both the epidemic and murine antigens, it was noted that in all tubes containing the epidemic antigen there was complete fixation regardless of the dilution of the test sera even when known negative sera were bening tested. As there was no parallel abnormal complement fixation in the presence of the murine antigen (the positive and negative controls gave expected results) the immediate suspicion was that the epidemic antigen had for some reason become anticomplementary. Another epidemic antigen was therefore used on the following day but the complement was unchanged. Again all tubes containing epidemic antigen gave complete fixation even with known negative sera while the series with murine antigen behaved as ex pected. It was obvious that we were not dealing with a chance phenomenon. The first thought, that the antigen had become anticomplementary, was improbable as our epidemic antigens had been recently shown to be free from anticomplementary action in the dilutions used. It seemed unreasonable to assume a sudden change in 2 antigens particularly as other similar antigens (murine) stored in the identical manner were unaltered.