Immunohistological characterisation of intraepithelial lymphocytes of the human gastrointestinal tract

Abstract

Intraepithelial lymphocytes (IEL) of the normal human stomach, small intestine, and large intestine have been characterised in tissue sections by a double marker immunofluorescent technique. A panel of reagents was used in combination, including antisera to T lymphocyte antigen (HuTLA), Ia-like (p28, 33) antigens and immunoglobulin subclasses, as well as a mouse monoclonal antibody to a human leucocyte antigen (HLe-1). In stomach and proximal small intestine over 95% of IEL were T lymphocytes (HLe-1+, HuTLA+). The proportion was slightly lower in the colon and rectum (85--95%). IEL rarely expressed Ia-like antigens. B lymphocytes were not seen within the epithelium of any of the tissues examined. The functions of IEL must be assessed in the light of the finding that they are predominantly T cells.