Effect of gluten-free diet on an immunological assay for coeliac disease.

The leucocyte migration inhibition factor (LIF) test for the presence of lymphocytes sensitised to gluten was evaluated over the past 4 years in patients with coeliac disease and correlated with the presence of gluten in the patients' diet. 149 LIF tests were done in 66 coeliac patients, 35 of whom were on a normal diet. However, 7 of 8 clinically and histologically diagnosed cases of coeliac disease who were LIF negative when first tested on a normal diet became LIF positive when placed on a gluten-free diet, so that 94% of patients with coeliac disease were LIF positive. On a prolonged gluten-free diet about 50% of LIF-positive cases became negative. The response to the LIF test seems to be related to gluten intake, with higher LIF values when the patient is taking gluten, and lower values when gluten is eliminated from the diet.