Intra-epithelial lymphocytes: interferon-gamma production and suppressor/cytotoxic activities

Human intraepithelial lymphocytes (IEL) proliferate minimally in response to phytohaemagglutinin (PHA), but produce as much interleukin-2 (IL-2) as do peripheral blood lymphocytes (PBL). The addition of sheep erythrocytes during activation of IEL with PHA markedly augments both T cell functions. This study evaluates the ability of IEL to produce interferon-gamma (IFN-gamma) and to develop suppressor and cytotoxic activities when stimulated with mitogens in the presence or absence of sheep erythrocytes. PHA-activated IEL produced as much IFN-gamma as did PHA-activated peripheral blood CD8+ T lymphocytes. IEL activated by concanavalin A (Con A) demonstrated less suppressor activity directed against T cell proliferation than did Con A-activated peripheral blood CD8+ T lymphocytes. IEL generated less mitogen-induced cellular cytotoxicity and lymphokine-activated killer cell activity than did peripheral blood CD8+ T lymphocytes. The addition of sheep erythrocyte lysates during mitogen stimulation of IEL markedly enhanced their proliferation and lymphokine production but did not affect their suppressor or cytotoxic activities.