[Interepithelial lymphocytes of small intestine]

The small intestine is a tissue which maintains contact with the external environment constantly. It receives antigenic stimulation and is attacked by various microorganisms at day and day base. The animals are then in danger without an efficient immune system of the gastrointestinal tract. The evidence described by this paper in the areas of morphology, position, structure, physiological phenomenon and immunologic functions, indicates strongly that IEL is a group of cells with important immunologic activities. In the last decade, technology to purify IEL has been improved, thereby enhancing immunologic research on this cell dramatically. Results disclose that immunologic activities such as ADCC, SCMC, NK, NC and CC are present in the IEL population. The surface maker studies on IEL in addition to the discovery of GML subpopulation further prove the immunologic importance of IEL. It is therefore believed at the present time that IEL is a combination of cells gathered at the intestinal mucosa in order to fulfill various local immunologic activities.