Detection of functional sFasL in the serum of tumor-bearing mice.

(A) Freshly isolated thymocytes from C57BL/6 +/+ mice stained with TdT + FITC-dUTP (bold histogram) or stained after irradiation and culture for 24 hours (broken histogram). (B-E) Thymocytes from C57BL/6 +/+ (B, D) or C57BL/6 lpr/lpr mice (C, E) were cultured in the presence of sera from PBS-treated control mice (bold histogram) or from tumor-bearing mice (broken histogram). Cells were analyzed for green fluorescence using a flow cytometer. The subtraction of broken histogram from the bold histogram has been indicated as the percentage apoptosis in each panel.