PASSAGE OF INGESTED PROTEIN INTO THE BLOOD DURING GASTROINTESTINAL HYPERSENSITIVITY REACTIONS - EXPERIMENTS IN THE PRERUMINANT CALF

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (3) , 575-582
Abstract
Preruminant calves given a series of feeds of heated soybean flour (HSF) frequently develop gastrointestinal hypersensitivity to soybean antigens. The permeability of the intestinal mucosa of calves undergoing hypersensitivity reactions to ingested HSF was assessed by feeding them milk and quantitating the leakage of .beta.-lactoglobulin into the blood. Maternal .beta.-lactoglobulin did not evoke an antibody response in calves. Therefore its detection in the serum was not influenced by immunological mechanisms that normally remove or exclude antigens from the circulation. In sensitized calves ingestion of HSF caused a dramatic increase in the permeability of the intestine to .beta.-lactoglobulin. The change was transitory and after 24 h permeability had almost returned to normal. The mucosal barrier was not permanently damaged regardless of the number of the severity of the reactions experienced. Indomethacin was ineffective in counteracting permeability changes. A progressive increase in the sensitivity of the gut to soybean antigens was accompanied by a rise in the titer of serum antibodies to soybean proteins. Absorbed .beta.-lactoglobulin was present in the serum in its monomeric form only, and quickly disappeared from the circulation. In an enzyme immunoassay used to measure its concentration absorbed .beta.-lactoglobulin was indistinguishable from the native protein. Measurement of intestinal permeability to macromolecules might be useful in the diagnosis of certain forms of food allergy in humans.