Frozen Toxin-Antitoxin Reactions

To the Editor: —At your request, we make the following statement concerning the effort of freezing on the toxin-antitoxin mixtures in the towns of Concord and Bridgewater, Mass.: A preparation of toxin-antitoxin was used in some forty children in January; the reactions were slight and such as were to be expected. During an intense cold spell, a number of vials of the same preparation were solidly frozen. When this toxin-antitoxin was melted and used for further injections, severe local reactions and constitutional disturbance followed. This preparation, when tested in the antitoxin laboratory in Boston and in the Hygienic Laboratory in Washington, was found to produce in animals the normal reactions, but, after freezing, became toxic. Other preparations tested in Boston, New York and Washington failed to show any increase in toxicity after thorough freezing. Since this occurrence, investigation has shown that several hundreds of children have been treated with other