Further notes on modification of diphtheria toxin by formaldehyde / by A.T. Glenny, Barbara E. Hopkins, and C.G. Pope.

  • Glenny, A. T.
Date:
[1924?]
Catalogue details

Licence: In copyright

Credit: Further notes on modification of diphtheria toxin by formaldehyde / by A.T. Glenny, Barbara E. Hopkins, and C.G. Pope. Source: Wellcome Collection.

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    of the original toxin. We have found that this concentrated toxin is easily modified by the addition of formalin, and that modified toxin can he concentrated by the process of Watson and Wallace. Since we prepared the concentrated modified toxin described below, onr colleagues have successfully concentrated a number of other similar batches. A hatch of diphtheria toxin was kept for eleven days at a temperature of 30° C. after the addition of 0*4 per cent, formalde¬ hyde. Some of the modified toxin so formed was concentrated by adding l/0 per cent, acetic acid, filtering and redissolving the precipitate in dilute alkali. The various measurements of the original toxin (J. 3460) after modification (PX. 57) and after concentration to one- twentieth of the original volume (PX. 76) are given in table II. Table II. Showing the strength of a toxin before and after modification with formaldehyde, and after modification and concentration. J. 3460. Original toxin. PX. 57. J. 3460 after treatment with formaldehyde. PX. 76. PX. 57 after precipita¬ tion with acetic acid. Minimal lethal dose 0-002 c.c. over 5-0 c.c. about 5-0 c.c. Minimal reacting dose . 0-0000015 c.c. over 0’2 c.c. 0-1 c.c. Li • • • • CP12 c.c. Lo • • • . 0-12 c.c. • • • • • • L . 0*14 c.c. • • • , , , Lf CPU c.c. CP14 c.c. (P01 c.c. Modified toxin is a more powerful antigen than toxin-antitoxin mixtures; its antigenic value can be greatly increased by concentration. The antigenic values of modified toxin before and after concentration were tested in the usual way; guinea-pigs injected with various doses of the antigen were given weekly Schick tests commencing three weeks after the initial stimulus, the number of the Schick dose that failed to produce a reaction being called the immunity index (Glenny, Allen, and Hopkins, 1923). For comparison in table III. we have given the results obtained from testing a batch of toxin-antitoxin mixture containing one-tenth of an L+ dose per c.c.; this mixture was kindly supplied by Dr Park of Xew York. It will be seen that guinea-pigs were invariably immune three weeks after the initial injection of 5‘0 c.c. of modified toxin PX. 57. The antigenic value of this modified toxin is not so good as that of the toxins only partially modified which we have tested (Glenny and Hopkins, 1923). It is possible that the original toxin of this preparation was weaker in true antigenic value than the toxin which had previously been only partially modified. On the other hand, we have considerable evidence that, unit for unit, the antigenic value of
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