Lymphocyte chemotactic activity of CXCL11 isoforms. CXCL11(1-73), CXCL11(3-73), CXCL11(5-73), and CXCL11(7-73) were tested for the ability to induce a chemotactic response on PHA- and IL-2–activated lymphocytes. Results represent the mean (± SEM) chemotactic index of 3 or more independent experiments. The Mann-Whitney U test was used for statistical analysis (*P < .05; ***P < .001 for a positive chemotactic response compared with buffer controls).