KGF and the RAG2^−/− thymic environment.

(A) The medullary compartment of the RAG2-deficient thymus. (i) The medullary compartment of RAG2-deficent mice defined by the 3G10 reactivity. Scattered dots represent endogenous peroxidase activity. Magnification × 35. (ii) Analysis of thymus chemokine expression. RNA samples from wild-type (WT) and RAG2^−/− thymi were treated with DNAse and then subjected to RT-PCR using a panel of chemokine primers. (B) Thymus tissue from RAG2^−/− mice receiving repeated intra-peritoneal administration of vehicle (i, ii) or KGF (iii, iv) were processed for immunohistochemistry. The distribution of all epithelial cells was detected by an antibody against E-cadherin (i, iii), and the distribution of medullary epithelium with 3G10 antibody (ii, iv). Asterisks indicate cystic structures in the KGF-treated RAG2^−/− thymus. Intact day-16 FTOC from C57Bl/6 mice cultured for 7 days in the absence (v) or presence (vi) of KGF at 100 ng/mL and then stained with 3G10 to demonstrate the medullary TE compartment. Panels i-iv, magnification × 40; panels v, vi, × 50. (C) RT-PCR analysis of chemokine mRNA expression in RAG2^−/− thymi treated with vehicle or vehicle containing KGF. Representative of 2 independent experiments with groups of 4 mice.