Concerning the Absorption of Unsplit Protein Through the Lacteals.

Abstract

It is commonly assumed that allergic responses to ingested foods are due to the passage of unchanged protein from the bowel into the blood. Alvarez, who had seen a few cases in which unfavorable reactions to food appeared to be worse when patients ate much fat with the offending protein, suggested to me that an unguarded pathway might be through the lacteals and thoracic duct into the blood stream. In this way the protein would escape possible change in the intestinal wall and in the liver. Somewhat in favor of this view is the reported observation that food reactions are less likely to occur if the patient first takes a dose of hydrocarbon oil; theoretically, it might block the lacteals. A number of investigations, inspired by the contributions of Uhlenhuth, and of Hamberger and Sperk, attempted to identify unchanged protein in the blood of animals by means of the precipitin reaction, but unfortunately the results were conflicting. The studies of Hektoen, Kanai, and Dragstedt may be mentioned in this regard. The difficulties in detecting foreign protein in the blood by precipitin methods are considerable, not only because the material is so greatly diluted, but, as has been frequently shown, because it leaves the blood stream so rapidly. The work of Walzer and of Smyth and Stallings, in which the newer principle of passive transfer in human beings was utilized, indicated that a detectable amount of certain proteins frequently enters the blood in unaltered form by way of the intestine. More recently, the experiments of Nedzel and Arnold on the influence of egg-white on the absorption of bacteria from the intestinal tract, and the studies of McDaniels on the effect of egg white in oral vaccination of mice against pneumococci, have given new impetus to studies in this field. Conclusion. In the dog, absorption of unaltered egg-albumin from the intestinal tract by way of the lacteals and thoracic duct could not be demonstrated.