An easy method to quantify plasma cells in caeliac disease.

Background: Caeliac disease is a common immune-mediated condition in the proximal small intestine, generated by a permanent intolerance to cereal gluten proteins in genetically predisposed individuals. It has become apparent that abnormal microbiota proliferate in the duodenal lumen of patients with caeliac disease. Recently it was also noticed that an antibody against multiple myeloma oncogene I/IRF4 (MUM1) stained plasma cells and their precursors. Materials and Methods: Eleven consecutive duodenal biopsies were investigated; four had villous atrophy (caeliac patients) and the remaining seven exhibited histologically normal mucosa (non-caeliac patients). Sections were stained with H&E and with anti-MUM1. A graticulated eyepiece (10 mm, divided into 10x10 squares) was used for counting of MUM1-expressing cells in the superficial compartment (SC) and in the deep compartment (DC) of the lamina propria mucosa (lpm). Results: In the duodenal mucosa of caeliac patients the mean number of MUM1-labelled cells in 12 areas of the lpm was 67.1 (range 37-88) in the SC and 61.5 (range 42-84) in the DC. In the duodenal mucosa of non-caeliac patients, the mean number of MUM1-labelled cells in 21 areas of the lpm was 7.6 (range 0-24) in the SC, and 29.2 (range 22-40) in the DC (p<0.05). Conclusion: These preliminary results showed that a significantly higher number of plasma cells/plasma cell precursors accumulate in the lpm in patients with caeliac disease, particularly in the SC. This abnormal accumulation of MUM1-expressing cells might be a defence mechanism against the alien bacterial flora recently reported in the duodenal microenvironment in caeliac patients. This appears to be the first report in which MUM1 immunostaining is applied to assess the frequency of plasma cell precursors in the duodenal mucosa in caeliac patients.