Lymphokine secretion and proliferation of intraepithelial lymphocytes from murine small intestine

Compared to other peripheral lymphocytes, intestinal intraepithelial lymphocytes (IEL) have previously been shown to have low proliferative capabilities. However, there are two main populations of IEL in the small intestine of mice. First, there is the thymus-dependent CD3+,Thy-1+ population, most of which expresses the alpha beta T-cell receptor (TcR), and second there is the thymus-independent CD3+,Thy-1- population, most of which expresses the gamma delta TcR. In this study Thy-1-enriched and Thy-1-depleted lymphocytes from murine intestinal epithelium were studied separately for their ability to proliferate and secrete lymphokines in vitro after mitogenic stimulation, after stimulation via the TcR-CD3 complex and after stimulation with the superantigen Staphylococcus aureus B (SEB). Here we show that Thy-1-enriched IEL are not an immunocompromised population of cells but are functionally competent T cells that are capable of proliferation and lymphokine secretion after stimulation with concanavalin A (Con A), phorbol myristate acetate (PMA) and anti-CD3 monoclonal antibody (mAb). Furthermore, Thy-1-enriched IEL proliferate and secrete lymphokines after 'superantigenic' stimulation with SEB. In contrast, the majority of Thy-1-depleted IEL do not proliferate, and secrete only minimal levels of lymphokine to any of the stimuli tested in this study.