CCL21 and colitis: Interestingly, to the best of our knowledge, we demonstrated that ILFs express CCL21 in the colon of OXZ mice, which is in good agreement with a previous experimental finding in the colon of DSS colitis mice49 and a previous clinical finding in humans that CCL21 is rarely expressed in lymph follicles of the normal colons, but is detected in lymph follicles of the inflamed colons in patients with IBD50.