Abstract
In a study of the reaction of children to Dr. Larsen's ricinoleated scarlet fever antigen, as determined by the Dick test, a wide diversity of response has been noted. Frequently children with positive Dick tests developed negative skin reactions, sometimes as early as 4 days, following the administration of antigen, but a return to the original state of skin sensitivity was observed in the majority in 6 to 8 weeks. Only a very few remained negative for as long as 6 months.
The variation in response is partially indicated by the following cases:
Following antigen administration a decrease in reaction was noted in almost all who originally showed a markedly positive test. In a small number of cases 2 doses of antigen or even 3 failed to produce a negative test, or at least one which persisted over periods varying from 3 weeks to 3 months. An increase in reaction was noted frequently after the giving of antigen, which as a rule tended later to decrease, but in individuals who were originally slightly sensitive might be marked and persistent.
Infants very rarely gave a positive reaction and were frequently negative to as much as 20 skin test doses. One infant, 2 weeks old, whose skin reaction was negative to 50 S. T. D., developed temporarily a positive Dick test, 16 days after the last portion of 900 S. T. D. of scarlet fever toxin (so-called) had been given.
The diversity of skin reaction, as indicated by the Dick test, following antigen administration, seems to find no parallel in the phenomena of true toxin reactions and antitoxin production. Nor does the development of a positive test in an infant previously negative, in response to treatment with scarlet fever streptococcus filtrate find its explanation on any but an allergic basis.
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