Imaging active lymphocytic infiltration in coeliac disease with iodine-123-interleukin-2 and the response to diet

Coeliac disease is diagnosed by the presence of specific antibodies and a j ejunal biopsy showing mucosal atrophy and mononuclear cell infiltration. Mu cosal cell-mediated immune response is considered the central event in the pathogenesis of coeliac disease, and untreated coeliac patients show specif ic features of T-cell activation in the small intestine. Here we describe t he use of iodine-123-interleukin-2 scintigraphy in coeliac patients as a no n-invasive tool for detection of lymphocytic infiltration in the small bowe l and its use for therapy follow-up, and we demonstrate the specificity of binding of labelled-IL2 to activated lymphocytes by ex-vivo autoradiography of jejunal biopsies. I-123-IL2 was administered i.v, [74 MBq (2 mCi)], and gamma camera images were acquired after I h. Ten patients were studied wit h I-123-IL2 scintigraphy at diagnosis and seven were also investigated afte r 12-19 months of gluten-free diet. Results were expressed as target-to-bac kground radioactivity ratios in six different bowel regions before and afte r the diet. At the time of diagnosis all patients showed a signifi- cantly higher bowel uptake of I-123-IL2 than normal subjects (P<0.003 in all regio ns). A significant correlation was found between jejunal radioactivity and the number of IL2R+ve lymphocytes per millimetre of jejunal mucosa as detec ted by immunostaining of jejunal biopsy (r(2)=0.66; P=0.008), Autoradiograp hy of jejunal biopsies confirmed that labelled-IL2 only binds to activated T-lymphocytes infiltrating the gut mucosa. After 1 year of the diet, bowel uptake of I-123-IL2 significantly decreased in five out of six regions (P<0 .03), although two patients still had a positive IL2 scintigraphy in one re gion. We conclude that I-123-IL2 scintigraphy is a sensitive non-invasive t echnique for assessing in vivo the presence of activated mononuclear cells in the bowel of patients affected by coeliac disease. Unlike jejunal biopsy , this method provides information from the whale intestine and gives a non -invasive measure of the effectiveness of the gluten-free diet.