CCL20 expression is up-regulated in spleen and thymus after mild TBI. A: Low magnification (scale bar 500 μ) photomicrographs showing the immunohistochemical labelling of CCL20 in spleen and thymus tissues in sham, and 24 h or 48 h after TBI. High magnification (scale bar 20 μ) images of the selected areas from each section are shown in the inset of the corresponding image. B. CCL20 immunoreactivity in spleen or thymus in sham or TBI animals was quantitated using the Image J program and expressed as mean area ± S.E.M. CCL20 immunoreactivity increased significantly 24 h and 48 h after TBI compared to sham animals. *p < 0.05, **p < 0.001 compared to sham. C. The histograms show the changes of CCL20 expression in spleen and thymus 24 or 48 hours post TBI. ELISA was performed with rat anti-CCL20 antibody using a Duo set ELISA kit from R&D systems. In both tissues CCL20 expression increased significantly 24 h after TBI. *p < 0.05, ** p < 0.001 compared to sham animals.