Lactase enzyme, detected immunohistochemically, is lost in active celiac disease, but unaffected by oats challenge.

OBJECTIVES: The loss of lactase activity that occurs in active celiac disease resolves on adherence to a gluten-free diet that excludes the cereals wheat, barley, rye, and oats. Recently, an immunohistochemical technique has been described to evaluate lactase expression in primary hypolactasia. We have adapted this method to study lactase activity in adult celiac patients and to assess its value as a diagnostic tool. In addition, given the results of two recent studies suggesting the safety of reintroducing oats cereal into the celiac diet, we have also evaluated the response of lactase expression to oats exposure.
METHODS: Duodenal biopsies from 26 patients were stained for lactase expression using an indirect immunoperoxidase method. Eleven disease control patients had normal architecture and nine had features of active celiac disease. Ten patients, who had celiac disease in clinical and histological remission, underwent oats challenge for 12 wk.
RESULTS: Confluent expression of lactase was observed in the 11 control patients with normal histology, whereas staining was absent in the nine patients with active celiac disease. All 10 patients with treated celiac disease had normal lactase expression after exposure to oats.
CONCLUSIONS: The immunohistochemical technique used in this study provides an easy, reliable method of assessing lactase enzyme and confirms the value of this index as a marker of celiac disease activity. The results of two recent studies demonstrating the lack of oats toxicity in adult celiac patients have been further corroborated by our findings, which show the preservation of lactase enzyme after oats challenge.