Transduction of human IL-9 receptor cDNA into TF1 cells induces IL-9 dependency and erythroid differentiation

Human growth factor-dependent cell line TF1, which lacks interleukin (IL)-9 receptors (R) and does not grow in IL-9, was transduced with a retroviral vector containing human IL-9R cDNA and a selection marker. An IL-9-dependen t TF1 cell line, which could also grow in other cytokines, was established after selection in G418 and could produce mature RBC in response to cytokin e stimulation. TF1 cells transduced with the same viral vector without the IL-9R insert cDNA (mock control) and then selected responded the same as no ntransduced TF1 cells. They failed to grow in response to IL-9 and did not generate RBC. An increased number and size of burst-forming units-erythroid (BFU-E)-like colonies were detected from IL-9R-transduced TF1 cells, compa red with mock-transduced cells, in response to erythropoietin (EPO) and IL- 9. To evaluate self-renewal and differentiation capacity, colony-replating assays were performed in the presence of IL-3, GM-CSF, IL-9, and EPO. After four replatings, the cloning efficiency of IL-9R-transduced TF1 cells decr eased from 98% to 38%, most likely due to terminal erythroid cell different iation. In contrast, no change in replating efficiency was detected in mock -transduced cells. TF1 cells stably expressing IL-9R and responding to IL-9 can serve as a cell line model to study the intracellular signals mediatin g IL-9-induced erythroid cell proliferation and differentiation.