Combined Schick test and diphtheria prophylactic : combined diphtheria-scarlet-fever prophylactic / A.T. Glenny and Hilda Waddington.

  • Glenny, A. T.
Date:
[1926?]
Catalogue details

Licence: In copyright

Credit: Combined Schick test and diphtheria prophylactic : combined diphtheria-scarlet-fever prophylactic / A.T. Glenny and Hilda Waddington. Source: Wellcome Collection.

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    p.*7rv Reprinted from THE JOURNAL OF PATHOLOGY AND BACTERIOLOGY, Vol. XXIX., 1926, pp. 118-122. tyt COMBINED SCHICK TEST AND DIPHTHERIA PROPHYLACTIC; COMBINED DIPHTHERIA-SCARLET-FEVER PROPHYLACTIC. A. T. Glenny and Hilda W addington. Wellcome Physiological Research Laboratories, Beckenham, Kent. Combined Schick test and diphtheria prophylactic. The Schick dose of toxin has a small immunising effect in animals already immune but its antigenic value as a primary stimulus is negligible. A pre¬ paration that would give a satisfactory Schick reaction and at the same time act as an immunising agent would have a distinct advantage as it would reduce the number of subsequent prophylactic injections for human beings from 3 to 2. It would also act as the commencement of a second course of immunisation in the small number of children who, when tested after a first series of inoculations, prove to be still positive to the Schick test. If such a preparation can be made of equal antigenic value to the diphtheria immunising agents already in use it might displace them entirely, for each injection would record the stage of immunisation reached. Such a diagnostic and prophylactic mixture (D.P.M.) must contain a relatively large amount of toxin or toxoid so masked with antitoxin that the total toxin free is the same as that in Schick toxin in order to produce corresponding reactions, and any excess toxoid must be in such a form that its presence will not interfere with the combining power of the toxin; thus the mixture will still detect the same level of immunity as the ordinary Schick dose of toxin. For some years we have been endeavouring to produce a satisfactory mixture; at first we hoped to be able so to modify toxoid that its affinity for antitoxin would be far less than that of toxin and that its addition to Schick toxin would not interfere with the combination of the toxin with any antitoxin presented to it. If such a mixture were injected into an animal with a small degree of immunity the antitoxin present in the blood would neutralise the same amount of toxin in the mixture as it would in a Schick dose of toxin without combining with the toxoid of weaker affinity ; this would then be free to act as an immunising agent. These experiments have been unsuccessful but preliminary work on a mixture consisting of a suspension in ordinary Schick toxin of toxoid precipitated by alum are giving promising results. The diagnostic and prophylactic mixtures described in this paper consist of toxin partially neutralised by antitoxin and diluted until the amount of toxin free was the same as in Schick toxin. It was necessary to test many batches of toxin before a suitable one could be found. The ratio of toxin to toxoid and consequently the ratio of toxin to combining power in a partially neutralised toxin is always less than in the original toxin. The Schick test dose (or our desired double Schick test and mixture) must contain a fixed amount of free toxin and must possess a definite combining power. Too little free toxin will lead to indefinite reactions; too much toxin would cause too severe reactions in the non-immune. The combining power must be fixed so that a constant level of immunity is detected by the presence or absence of a reaction. The following tests serve to show that the diagnostic value of the diagnostic pro¬ phylactic mixture (DPM) is approximately the same as Schick toxin.