Reverse transcriptase quantitative (q)PCR analyses of interleukin (IL)-4 receptor (R)/IL-13R mRNA expression . (a) Ethidium bromide gels of PCR products after 35 cycles of qPCR with cDNAs from cultured indicated cells with indicated primers. Tenocytes (Tenoc) expressed scleraxis mRNA, confirming the phenotypic identity of these cells. Tenocytes and pulmonary fibroblasts but not T cells expressed mRNA for collagen chains. All tested cell types expressed IL-4Rα mRNA, and all cell types except T cells expressed IL-13Rα1 and IL-13Rα1 mRNAs. Only T cells expressed common gamma chain (γc). (b) Quantitative analyses reveal relative expression of receptor chains in cultured tenocytes from indicated tendons of five separate donors (SYBR Green-based quantification, normalized to 18S rRNA). The prime marks indicate separate cultures developed at a different time from the same tissue source and analyzed at a different passage. A549 = transformed pulmonary epithelial cell line; NHLF = normal human lung fibroblasts, PBMC = peripheral blood mononuclear cells from a healthy volunteer.