Intraepithelial lymphocyte mitosis in a jejunal biopsy correlates with intraepithelial lymphocyte count, irrespective of diagnosis.

When there is villus atrophy in a jejunal biopsy, intraepithelial lymphocyte (IEL) mitosis correlates with a diagnosis of coeliac disease. We have examined the significance of IEL mitosis in jejunal biopsies with normal villi. Counts of IEL per 100 villus enterocytes, and IEL mitosis per 1000 IEL, were carried out in 81 jejunal biopsies. Thirty one were from patients with coeliac disease or dermatitis herpetiformis, and many of these, from treated patients, were histologically normal; 40 were from patients with other diagnoses, selected to include biopsies with a high IEL count (greater than 40 IEL per 100 enterocytes) but normal villi. Three coeliacs and 10 dermatitis herpetiformis patients had an IEL count of less than 40, and no IEL mitoses were found in these biopsies. Two dermatitis herpetiformis patients had IEL counts of 43.7% and 43.9%, with no IEL mitoses, but in all other coeliac and dermatitis herpetiformis biopsies high IEL counts were associated with IEL mitotic indices between 0.05% and 1.77%. In the non-coeliac, non-dermatitis herpetiformis group, no IEL mitoses were found in the 22 biopsies with IEL count less than 43%. In the others, IEL counts ranged from 44.8% to 127.0%, and IEL mitoses were present, with mitotic indices ranging from 0.06% to 0.49%. This work shows that IEL mitosis in a jejunal biopsy is not specific for coeliac disease, but occurs whenever there is an increased density of IEL within the villus epithelium.