TUNEL assays on 2 follicular lymphoma patients. (A-B) Patient 1. Follicular lymphoma with high level of bcl-xL gene expression. (A) A malignant follicle (surrounded by dotted line) is negative. TUNEL assay; original magnification, × 200. (B) Higher magnification of the malignant follicle. Typical malignant centrocytic cells with cleaved nuclei (arrowheads) are negative. TUNEL assay; original magnification, × 700. (C-D) Patient 2. Follicular lymphoma with low level of bcl-xL gene expression. (C) A malignant follicle (surrounded by dotted line) is composed of cells stained by TUNEL assay, when normal lymphocytes around the follicle (arrows) are negative. TUNEL assay; original magnification, × 300. (D) Higher magnification of the malignant follicle. Typical malignant centrocytic cells, with cleaved nuclei (arrowheads) stained. TUNEL assay; original magnification, × 800. (E) Kaplan-Meier survival curve for patients with follicular lymphoma according to bcl-xL gene expression. Overall survival of the patients with bcl-xL gene levels above the median (red line) was significantly shorter than that of patients with bcl-xL gene levels below and equal to the median (green line). (F) Kaplan-Meier survival curve for patients with follicular lymphoma according to number of apoptotic cells. Overall survival time of patients with fewer apoptotic lymphoma cells than the median (red line) was significantly shorter than that of patients with apoptotic cell numbers equal to or exceeding the median (green line).