ULTRASTRUCTURAL-CHANGES IN THE DUODENAL MUCOSA INDUCED BY INGESTED HISTAMINE IN PATIENTS WITH CHRONIC URTICARIA

Histamine in food may be responsible for some cases of food intoleranc e. We previously demonstrated disturbances in the metabolism of ingest ed histamine in patients with chronic urticaria (CU) and proposed that this could be related to increased intestinal permeability to histami ne. The present study was undertaken to look for ultrastructural chang es in the intestinal tract that might explain this abnormality. We exa mined duodenal biopsies from seven patients with CU before and after i ntraduodenal administration of histamine (120 mg). Five subjects had c linical symptoms (diarrhea, urticaria, headache, accelerated heart rat e, and drop in blood pressure) within 1 h of duodenal histamine challe nge (DHC). Ultrastructural changes, including edema of the interstitia l tissue, enlargement of the basal intercellular spaces, slight conges tion of the endothelial cells, and pericapillary edema, were observed in six subjects 45 min after DHC. In all the biopsies, the epithelium was normal, and the tight junctions were not modified by DHC. This mor phologic study demonstrates that histamine can induce edema in the bas al intercellular spaces of the duodenal mucosa and in the submucosa wi thout evident change in the integrity of intercellular junctions. The most plausible route for histamine to have taken would appear to be an intracellular one.