Expression of β7 Integrins and Other Cell Adhesion Molecules on Mouse Lymphocytes and Their Modulation by a New Cytokine, IL-2 Receptor-Inducing Factor

We explored the role of a new cytokine, IL-2 receptor-inducing factor (IL-2RIF), in intestinal mucosai immunity and in the regulation of integrin β7 receptors on intestinal lymphocytes. Most SIEL (small intestine intraepithelial lymphocytes) were M290 (αM290β7) positive, while only 10 to 15% of SIEL were R1-2 (α4) positive. The expression of α4 (R1-2) and β7 (M293) but not αM290β7 integrin on SIEL was up-regulated by IL-2RIF. Incubating SIEL with IL-2RIF resulted in the up-regulation of CD45RB and down-regulation of CD44. About 50% of LPL (lamina propria lymphocytes) were αM290β7 positive, while only 20% of LPL were α4 positive. The expression of αM290β7 integrin on LPL was down-regulated and α4 and β7 integrin was up-regulated by IL-2RIF. Incubating LPL with IL-2RIF resulted in the up-regulation of CD44 and no significant change of CD11a, CD45, CD45RB, and ICAM-1. These results suggested that SIEL and LPL may play a different role in intestinal mucosal immunity and that IL-2RIF may play an important role in regulating the functions of integrins β7 on IEL and LPL.