Titration of Diphtheria Toxin and Antitoxin on Hamsters.

Abstract

The use of guinea pigs in the titration of diphtheria toxin and antitoxin, while being a standard method, is not without its drawbacks. The animal is not always procurable and its cost of purchase and maintenance is comparatively high. The Ramon precipitation method is simple and economical, but the results are not always quite satisfactory or conclusive. Furthermore, we are not without misgivings in the titration of a biological phenomenon by purely chemico-physical means, at least not without further understanding of the nature of their correlation.

In an attempt to discover a method of titration which can be applied when guinea pigs are not available, we find that the results obtained by standardizing diphtheria toxin and antitoxin on hamsters are comparable to those obtained by the use of guinea pigs.

Throughout the experiment hamsters, Cricetulus griseus, weighing from 25 to 30 gm. are used. They are easily obtainable in this part of the world and are quite susceptible to diphtheria toxin. The diphtheria toxin we use is from the National Epidemic Prevention Bureau, Peiping. Its M.L.D. for guinea pig is 0.005 cc. and its L + dose 0.22 cc. The antitoxin is obtained from the same source and checked by us against the standard unit provided by the U. S. Hygienic Laboratory, Washington, as containing 350 units per cc. They are diluted to the required concentrations with 0.9% saline. In case both toxin and antitoxin are injected into the same animal, they are always mixed in vitro and allowed to stand one hour before injection. The total amount injected is 1 cc. and all injections are given subcutaneously.

Three sets of experiments are performed. One sample test from each set is reported in this communication.