The standardisation of tuberculin / by A.J. Eagleton.

  • Eagleton, A. J.
Date:
[1921?]
Catalogue details

Licence: In copyright

Credit: The standardisation of tuberculin / by A.J. Eagleton. Source: Wellcome Collection.

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    in 24 hours, taking three days to reach their maximum development. The control injection gives a transitory reaction, but this fades by the second or third day, while the different dilutions of tuberculin give rise to lesions of varying intensity. In the most marked, a central area of necrosis is surrounded by a bright red halo, the whole mounted on an oedematous disc with a sharply defined border. The slighter degrees are marked by diminishing necrosis until the end¬ point consists merely of a small raised disc; often, however, there is a sudden transition from a lesion showing necrosis to a completely negative reaction. The von Pirquet and intracntaneons tests can be used for the standardisation of tuberculins, but hitherto we have always checked the results so obtained by the subcutaneous method. The skin reactions are, however, indispensable in experimental work, where we have a large number of samples made in different ways, where the available material is small, or where we must test for small traces of active principle. It should be pointed out that in all cases where the skin tests are used alone, a control and the standard must be included on the same animal as the samples under experiment. Slight individual variations occur in the members of a batch. These are due partly to the differences in the skin trauma, and partly to the fact that the skin reactions, being more delicate, detect variations which do not affect the subcutaneous test. The value of the von Pirquet test as a guide to the sensitivity of a batch, and the comparison of the skin reactions with the subcutaneous test, are shown in the accompanying table. 4. Constancy of Test. Since August, 1919, when our present standard was adopted, 13 different batches of animals have been infected with a constant dose of the same culture. Of these animals 91 have received doses of standard ranging from l'O c.cm. to 0’025 c.cm. In only two cases were irregular results produced with animals of the same batch—that is, a low dose killed, while a higher dose was ineffective. The individual variation of members of the same batch gives an error then of just over 2 per cent. The constancy of the test on all batches is shown in the diagram. It represents animals injected with tuber¬ culin at least 80 days after infection. The tops of the black columns show the percentage of deaths at each dose. The tops of the shaded columns show the increased percentage of deaths since we have employed the von Pirquet test to indicate the dosage for sub¬ cutaneous inoculation,