THE INTERACTIVE ROLE OF MUCOSAL T-LYMPHOCYTES IN INTESTINAL GROWTH, DEVELOPMENT AND ENTEROPATHY

Over the past 15-20 years, research has progressively focused on the m ucosal T cell as the central factor in the initiation of physiological or pathological changes, first in the growth and maturation of the ea rly (postnatal) intestine, and second in adult-type enteropathies resu lting from sensitivity to either food or pathogen-derived antigens. T cell-mediated events may be measured, for example, in terms of specifi c immunopathologic patterns of change and injury, such as type 1 (lymp hocyte infiltration), type 2 (crypt hyperplasia) and type 3 (flat-dest ructive), which can be recognized and quantitated microscopically; by determination of lymphocyte reactivity through secretion of interleuki n-2 receptors (IL-2R) into plasma or expression by mucosal lymphocytes ; by quantitation of lymphocyte subsets emigrating into inflamed tissu es by immunoperoxidase-labelled monoclonal antibodies; or by the deter mination of T cell receptor polymorphisms. Alterations in intestinal g rowth, structure and function at weaning are likely to be T cell-media ted as they are analogous to the same type 1/2 lesions that reflect mo dulation of adult mucosal architecture in food and parasite-induced hy persensitivity reactions. Enteropathies associated with HIV infection and T cell deficiency display a milder degree of villous flattening an d impaired crypt hyperplasia than that typical of gluten-sensitivity, suggesting a reversion to lesser degrees of mucosal pathology (type 1/ 2). Clearly more information will accrue; meanwhile the remarks in thi s brief survey should provide a firm basis whereby clinician and scien tist can meet, and together recognize and further dissect the modulato ry effect of T lymphocytes on mucosal structure and function.