Reversal of IgM deficiency following a gluten-free diet in seronegative celiac disease

Figure 3 Duodenal biopsy specimens before (A) and 12 mo after (B) gluten-free diet in our patient with Selective IgM deficiency and seronegative celiac disease. Immunohistochemistry showed scarse MUM1 plasma cells before the diet and a marked positivity 12 mo later. Positive cells are stained brown and counterstained blue (× 200).