Regulation of lung CD72 expression by allergen and VEGF. Sema4D receptor CD72 expression in mouse lung tissue and cells was analyzed by immunohistochemistry and flow cytometry (A-B). (A) Formalin-fixed paraffin-embedded lung tissue sections obtained from either control or OVA-treated WT mice were deparaffinized and immunohistochemistry was performed using appropriate Abs as described in Materials and Methods. Frozen lung tissue sections were used for VEGF tg mice. CD72 is the most abundantly expressed molecule in the lungs of PBS-treated mice. Its expression is further upregulated with OVA treatment. Note that subsets of inflammatory granulocytes and lymphocytes express CD72 (red arrow). In VEGF tg lungs CD72 expression was mainly targeted to inflammatory macrophages (red arrow). Red arrowhead points to the lung epithelial cell CD72 expression. (B) CD72 is expressed on lung MHCII+ cells including DC and is upregulated by OVA. Both CD4+ and CD8+ T cells in the lung express CD72 at low level which is further upregulated by allergen on CD4+ T cells.