Murine DCs express Fas but are resistant to Fas-ligation-induced apoptosis. (A) Flow cytometric analysis of Fas expression on the surfaces of C57BL/6J thymocytes and DCs stimulated with different agents. The top panel compares Fas expression in DCs at both stages (ii shows immature DCs; iii, LPS-matured DCs) and in thymocytes (iv). The bottom panel compares Fas expression in immature DCs (ii) and in immature DCs stimulated with anti-mCD40 (vi) or IFN-γ (v). i indicates control. (B) Immature DCs (IDC) and mature DCs (MDC) from normal C57BL/6J mice and thymocytes from normal C57BL/6J mice (NT) or lpr mice (lprT) were treated with 1 μg/mL or 5 μg/mL of either Jo-2 or isotype antibody for 8 hours. The percentage of apoptotic cells was quantified by staining with Annexin V-FITC and PI. Annexin V single-positive cells, PI single-positive cells, and Annexin V and PI double-positive cells were considered apoptotic. Plots are labeled with the percentages of gated cells that expressed either or both apoptotic markers.