The intestinal absorption of antigenic protein by normal infants.

Abstract

In previous communications, 1 it has been shown that the blood of most marasmic infants contains precipitin for cow's milk at some period of the disease, indicating preceding enteral absorption of antigenic protein from cow's milk.

Supported by a large number of observations, it is generally assumed that in the process of normal digestion no antigenic protein product enters the blood. In a few isolated experiments, which involved feeding large amounts of protein at a single dose, absorption of antigenic protein by normal individuals has been demonstrated by Ascoli, Schloss and Worthen, and others. Most investigations of this type, however, have been negative. In a large number of normal infants, tests for precipitin for cow's milk made by us, have been uniformly negative.

The fact that precipitin for cow's milk may be present in the blood of marasmic infants for a time but later disappear, despite the continued ingestion of cow's milk, suggested that perhaps a similar process may occur with normal infants. If this were true, normal infants might absorb antigenic protein in amounts sufficient to provoke the production of precipitin for a short time only, in which event negative precipitin tests would not prove that antigenic protein were not absorbed at some previous time. It therefore seemed desirable to observe normal infants whose food contained proteins which they had not ingested before, and to determine whether sufficient antigenic protein was absorbed from the intestinal tract to cause the appearance of specific precipitin. Pursuant of this, observations were conducted on normal infants who received egg white, sheep serum and almond in their food. We have had opportunity also to observe normal infants who received cow's milk for the first time.