The standardisation of tuberculin and the precipitin test / by C.C. Okell [and others].

Date:
1926?]
Catalogue details

Licence: In copyright

Credit: The standardisation of tuberculin and the precipitin test / by C.C. Okell [and others]. Source: Wellcome Collection.

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    9 Table I. A = Description in Table VII. (Dreyer and Vollum, 1924). B = Value by precipitin test (Dreyer and Vollum). C = Value by guinea-pig test (Okell and Parish). A. B. C. A. B. C. British 3 . . 33-2 100 British 2 .. 135-1 100 4 46-0 100 „ 8 . . 119-6 100 ” 5 . . . . 244-7 100 „ 9 .. .. 95-2 100 American 29 131-3 10 „ 12 .. .. 117-8 100 Belgian 30 19-8 5 „ 26 .. .. 6-4 10 American 27 14-8 10 28 . . 29-6 20 French 31. . 18-3 10 It therefore became of fundamental importance to discover whether tuberculins found to be equal (within the error of the test) to standard by the official Frankfort test on guinea-pigs could vary widely in their content of the active principles of “ tuberculin,” the substance used for the detection of tuberculosis in man and animals. A joint investi¬ gation was therefore arranged. It was agreed that one of the workers at the Wellcome Physiological Research Laboratories should choose from materials available at the laboratories three tuberculins, and should hand them to the various workers, each of whom would know nothing of the value of the tuber¬ culins or of results obtained by the other workers until he had made his final report. The three tuberculins were 1366, a Koch’s old tuberculin made on the ordinary glycerine veal broth medium, 1360, and 1232. These two latter had been made in the ordinary way from strains of B. tuber¬ culosis grown as a film on glycerine veal broth in the expectation that good tuberculin would result. When the filtrates had been concentrated and batches of the desired Koch’s old tuberculin had resulted, the “ tuberculin ” failed to pass the ordinary animal test. Further examination by the various guinea-pig tests indicated that the “ tuberculin ” values of these two batches were very low—approximately 2 to 5 per cent, and 5 to 10 per cent. In order that the various workers should use the same technique, Dreyer and Vollum arranged a full demonstration of the details of the precipitin test at Oxford. This enabled Okell, with the help of Miss G. I. Steed, to carry out three precipitin tests on the three tuberculins. These latter workers with their limited experience of this test would not attach undue importance to the accuracy of their figures obtained by the precipitin method. However, in their three tests they always placed the three tuber¬ culins in the same order of merit (Col. 7) as Dreyer and Vollum (Col. 6, Table II.). Cummins carried out the testing of the three tuberculins on a number of patients. He decided to test out these tuberculins in a series of dilutions as formerly suggested by Dreyer and according to the technique described by himself (1924). This same technique was used by Dreyer and Vollum in the “ human cutaneous test ” described in their paper