GRO is Chemotactic for Human Intestinal Intraepithelial Lymphocytes

: Human intraepithelial and lamina propria lymphocytes are memory lymphocytes that migrate from the circulation to the intestinal mucosa. We studied the effect of the chemokine, GRO, on these lymphocytes. Intraepithelial and lamina propria lymphocytes were isolated from human jejunal mucosa of healthy individuals and cultured for three days in IL-2. Migration was assessed using the Boyden transwell assay. Increases in cytoplasmic free calcium concentration were measured by changes in fluorescence of Fura-2-loaded lymphocytes upon exposure to GRO. A large number of intraepithelial lymphocytes (IEL) but few lamina propria lymphocytes (LPL) migrated toward GROα, GROβ, and GROy. Checkerboard experiments showed that the response of intraepithelial lymphocytes was mainly by chemotaxis rather than chemokinesis. The action of GROa was independent of cytochalasin D, staurosporine, and pertussis toxin but was inhibited by sodium azide and cycloheximide. None of the GRO proteins triggered calcium mobilization by either lymphocyte type. This study shows that GRO is chemotactic for IEL but not LPL.