Abstract
A study was made of the antigenic changes that result when milks are boiled, evaporated, superheated, dried or acidified. This was done to determine why individuals sensitive to raw or pasteurized milk can generally tolerate milks modified by heat.
The milk proteins were purified and their immunochemical reactions studied by the anaphylaxis method in the guinea pig. It was found that the proteins isolated from raw milk are chemically and biologically distinct.
The immunochemistry of evaporated, superheated, freshly boiled, acidified and dried milks and their immunological relation to the purified proteins from raw milk were studied. It was found that there were no antigenic changes as a result of drying, acidification or pasteurization. Milks that were dried, acidified, superheated or evaporated showed no loss in the antigenic properties of the casein fraction. As a sensitizing agent, given by injection, evaporated, freshly boiled and superheated milks showed practically no loss in the antigenic character of the lactalbumin fraction but as a shock agent these milks showed an unmistakable loss in the antigenic properties of the whey proteins.
Raw and the various modifications of milk described above were fed to a large number of guinea pigs. Evaporated, freshly boiled and acidified evaporated milk, when fed, showed a marked reduction in sensitizing ability. The acidified raw, dried and superheated milks did not differ from the raw milk.
A human case markedly sensitive to lactalbumin was studied immunologically. This patient developed anaphylactic shock with recovery when given 0.02 cc. of a 1% solution of pure lactalbumin intracutaneously. The blood serum containing lactalbumin antibodies passively sensitized normal guinea pigs and the skin of normal human recipients. The child was shown to tolerate evaporated milk in large amounts although raw milk, taken by mouth, in very small amounts produced anaphylactic reactions.
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