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Two classes of effector T cells exist. The first is normally CD4+, has a TCR associated with CD3 and interacts with foreign peptides bound to MHC Class II antigens on antigen presenting cells. The second, is CD8+, has TCR-CD3 and interacts with foreign peptides associated with Class I MHC molecules on target cells. However, little is known of the interaction between these differenteffector cells and intestinal epithelial cells. For this reason, the regulation of MHC molecules by two T cell products, IFN-γ and IL-4, was examined. Cytokines such as the IFN-γ produced by Th1 cells, induce MHC Class II expression on intestinl epithelial cells (IEC) both “in vitro”1 and “in vivo”2 but the effect on MHC Class I, and on cells at different stages of differentiation has received essattention. IL-4, a product of Th2 cells, is known to up-regulate Class II expression on B cells and monocytes3 but its effect on that of IEC has not been studied. We, therefore, used FACScan analysis to compare the expression of MHC antigens on human intestinal epithelial cell lines and the subsequent effect of a 48hr exposure to IFN-γ or IL-4. Furthermore, since IEC “in vivo” are present at different stages of differentiation depending on their location within the intestinal villus, two epithelial cell lines, representing different maturation states were compared. |
