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 mucosal T cell as the central factor in the initiation of physiological or pathological changes, first in the growth and maturation of the early (postnatal) intestine, and second in adult-type enteropathies resulting from sensitivity to either food or pathogen-derived antigens. T cell-mediated events may be measured, for example, in terms of specific immunopathologic patterns of change and injury, such as type 1 (lymphocyte infiltration), type 2 (crypt hyperplasia) and type 3 (flat-destructive), which can be recognized and quantitated microscopically; by determination of lymphocyte reactivity through secretion of interleukin-2 receptors (IL-2R) into plasma or expression by mucosal lymphocytes; by quantitation of lymphocyte subsets emigrating into inflamed tissues by immunoperoxidase-labelled monoclonal antibodies; or by the determination of T cell receptor polymorphisms. Alterations in intestinal growth, structure and function at weaning are likely to be T cell-mediated as they are analogous to the same type 1/2 lesions that reflect modulation of adult mucosal architecture in food and parasite-induced hypersensitivity reactions. Enteropathies associated with HIV infection and T cell deficiency display a milder degree of villous flattening and 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 this brief survey should provide a firm basis whereby clinician and scientist can meet, and together recognize and further dissect the modulatory effect of T lymphocytes on mucosal structure and function.
University Department of Medicine, Hope Hospital, Salford, Greater Manchester, United Kingdom.
M N
MN
Marsh
A G
AG
Cummins
D000818:Animals; D006087:Graft vs Host Reaction / Q000502:physiology; D006801:Humans; D007410:Intestinal Diseases / Q000473:pathology / Q000503:physiopathology*; D007413:Intestinal Mucosa / Q000196:embryology / Q000254:growth & development / Q000276:immunology* / Q000473:pathology; D013601:T-Lymphocytes / Q000502:physiology*