TGF-β1–induced regulation of Fas expression on Lin− BM cells. Fifty thousand Lin− BM cells were cultured in 96-well microtiter plates in complete IMDM and cytokines as indicated at predetermined optimal concentrations for 44 hours at 37°C and 5% CO2 in air. Freshly isolated thymocytes (A), Lin− BM cells (B), as well as cultured Lin− cells (C through F ) were stained with an FITC-conjugated anti-Fas antibody (Jo2) or irrelevant control hamster IgG and analyzed by flow cytometry as described in Materials and Methods. (C and D) Fas expression after culturing Lin− BM cells in GM-CSF for 44 hours, in the absence or presence of TNF-α, respectively. (E and F ) Fas expression of Lin− BM cells cultured in GM-CSF + TGF-β1 after 44 hours of incubation in the absence or presence of TNF-α, respectively. For all panels the Y-axis represents relative cell number and the X-axis represents relative fluorescence intensity. One representative experiment (of three) is shown. Gray lines represent the control antibody.
