Studies of intestinal lymphoid tissue: the cytology and electron microscopy of gluten-sensitive enteropathy, with particular reference to its immunopathology.

Knowledge of the cytology, ultrastructure and histochemistry of the small intestinal mucosa has advanced considerably over the last 20 years, particularly in regard to the changes associated with coeliac disease. Many of the known structural and cytological changes in coeliac mucosa are probably non-specific, and not directly related to its pathogenesis. It seems important to move away from purely descriptive images of mucosal abnormality such as "villous atrophy', and static measurements, such as crypt-villous ratios. Rather, the mucosa should be viewed as a dynamic, three-dimensional structure and evaluated in terms of total villous cell counts, crypt cell production rates, and so on. The organisation of the lamina propria is still poorly documented, and requires further exploration at the ultrastructural level. More thought should be given to the meaning of mucosal permeability and to its structural counterparts. The immunocytopathology of the coeliac lesion is far from understood; it is questionable whether local humoral activity is central to the pathogenesis of the condition. More needs to be learned of the role of T cells, not only in local mucosal reactions, but also in terms of possible regulatory effects on crypt cell kinetics, villous shape and hence mucosal structure. Increased mitotic activity of epithelial lymphocytes in coeliac disease appears to correlate exclusively with gluten-sensitivity and the use of this presumed immunological marker in the histological diagnosis, and thus prediction, of gluten-sensitised individuals is proposed in this paper.