The titration of diphtheria toxin by the flocculation method / A.T. Glenny and U. Wallace.

  • Glenny, A. T.
Date:
[1925?]
Catalogue details

Licence: In copyright

Credit: The titration of diphtheria toxin by the flocculation method / A.T. Glenny and U. Wallace. Source: Wellcome Collection.

    8/16 (page 324)
    Standard antitoxic serum. Curves 6, 7 and 8 in chart 2 show the time of precipitation, coarse flocculation, and deposition respectively in mixtures of the same toxin T.b. as in curve 3 and another antitoxin AT.2. kept at a temperature of 50° C. Thus it is seen that when the same toxin (T.b.) is titrated against antitoxin (AT.l.) a balanced mixture is produced by the addition of 11 \ units of antitoxin to 1 c.c. of toxin; if another antitoxin (AT.2.) is used, 28 units of antitoxin are needed to form the balanced mixture. The estimation of strength of this toxin depends therefore upon the antitoxin against which it is titrated. It is necessary there¬ fore to refer in our definition of an Lf dose to a “ certain chosen antitoxin.” We have chosen 1 Ehrlich unit of a certain antitoxin (AT.S.) determined by animal methods as the basis of standardisation; if now in place of titrating toxin T.b. against 1 Ehrlich unit of antitoxin AT.2., we titrate AT.2. against 1 Lf unit of toxin T.b. we obtain an in vitro unit value for AT.2. If the in vitro unit value is a definite strength then it should he possible to titrate other toxins by the flocculation method equally against 1 in vitro unit of AT.S. (accepted as equal to 1 in vivo unit) as against 1 in vitro ivnit of AT.2. independently of its in vivo value. Table III. Showing the strength of a number of different toxins in Lf units per c.c. determined by titration against in vitro units of different sera. Antitoxin used. AT.S. AT.2. AT.7. In vivo value 280 260 340 hi vitro value 280 110 260 Ehrlich units per in vitro units • 1-0 2*36 1-30 ( 9-0 8-2 9-2 3-2 • • • 3-2 6-4 • • • 7-4 5 '6 5-5 6-7 6-7 5-0 5-0 9-8 9-9 11-2 10-4 8-4 8-2 5-6 5-5 Lf units per c.c. . 7-0 4*8 6-6 4-7 7-7 7*7 5*6 6-0 3-6 3-8 5-6 5-5 17-5 16-9 16-3 8-25 7-0 8-6 27-0 26-2 27-0 8-25 7*8 9-3 21-0 18-6 20*8 16-0 16-8 16-7