The concentration of diphtheria toxin by acid precipitation / by A.F. Watson and U. Wallace.

  • Watson, A. F.
Date:
[1924?]
Catalogue details

Licence: In copyright

Credit: The concentration of diphtheria toxin by acid precipitation / by A.F. Watson and U. Wallace. Source: Wellcome Collection.

    11/12 (page 297)
    It would appear that outside conditions of temperature, etc., have resulted in the change of the active principle from the toxic to the toxoid state. The latter change has possibly not affected the combining value of the filtrate, as is suggested by the Lf values. It would seem that the animal tests show that the toxin of the filtrates is very susceptible to changes of temperature, etc. These changes, whilst affecting the toxicity, because they do not affect combining power, may not interfere with the antigenic value of the solution. It has been the experience during the present work to find the toxicity of the various reconstructed antigens rapidly falling off with increases in temperature and time (Watson and Wallace, 1924), whereas the Ramon flocculation titrations show a tendency to remain steady provided the temperatures to which the solutions have been exposed have not been too severe. It may be that these solutions which before the recognition of the Ramon test would have been regarded as low grade antigens may be found on experiment to be quite useful. 6. The concentration of chemically modified toxins. That toxic filtrates of B. cliplitherice may be so modified that whilst the actual toxicity is very considerably reduced the antigenic pro¬ perties remain unimpaired has long been recognised. Glenny and Sudmersen (1921) by modification with formalin were able to inject 5 c.c. of a filtrate into a guinea-pig without producing any injury although previous to the treatment the filtrate had killed in dilutions of 2J0 °f a cubic centimetre. When the concentration process outlined above is applied to filtrates modified with formalin it is found that provided the pre¬ cipitate has not been left for too long a period before centrifugation, a perfectly clear reconstructed antigen is obtainable and that the Ramon units have also been concentrated. Most of the work of the present paper was carried out before the general recognition of the value of Ramon’s work. Possibly a proportion of the loss occasioned during the process is due to the change of the active principle from a toxic to a toxoid state. If this change has proceeded sufficiently far the Lr/500 values would appear to indicate a loss of the active principle, and it would probably have been more satisfactory to employ the Ramon values as criteria of the activity of the various filtrates and reconstructed antigens. It is possible by precipitation methods to obtain solutions which give very high Lf values. Thus by using the method described above, reconstructed antigens which gave Lf values in dilution as low as 0'017, 0'005 and even 0'002 c.c. have been obtained. Work is being continued on these solutions, which must, if the Ramon titrations are proved to be criteria of antigenic value, be of great importance to the immunologist.