Figure 2.

Details of TUNEL and lymphocyte marker double staining of lymph nodes. TUNEL is stained with DAB-black (black) and Fas (A), FasL (B), CD3 (C), or CD20 (D) with DAB (brown). (A) A view of the paracortical region showing the difference between a TUNEL⁺/Fas⁺ cell (arrowhead) with brown cytoplasm around the black nucleus, and a TUNEL⁺/Fas⁻ cell (arrow). In the latter, the cytoplasm is clear. (B) In the paracortical area, FasL was seen in high endothelial venules (HEVs) and in 70% of TUNEL-positive cells (arrowheads). (C) Apoptotic T-lymphocytes (TUNEL⁺/CD3⁺ double-positive cells) were only seen in the paracortex (arrowhead). (D) Within the germinal centers, TUNEL⁺/CD20⁻ cells were frequently seen (arrows). Bar = 20 μm.