Double immunofluorescence staining for interleukin (IL)-6 and ED-1 or T-cell receptor (TCR). Representative sections through ipsilateral lumbar dorsal root ganglia (DRG) illustrate double immunostaining (A,D) for IL-6 and (B) ED-1, indicating invaded macrophages, and/or (E) TCR, a common marker of T cells. (C,F) Merged pictures show that ED-1+ macrophages and T cells (arrowheads) may contribute to IL-6 protein increase in lumbar DRG after chronic constriction injury (CCI) of the sciatic nerve. Sections were cut through ipsilateral lumbar DRG of rats subjected to unilateral CCI of the sciatic nerve for 3 days. After incubation with (A,D) rabbit polyclonal anti–IL-6 and (B) mouse monoclonal anti-ED-1 or (E) anti-TCR, the sections were treated with affinity-purified antibodies: (A,D) tetramethyl rhodamine isothiocyanate (TRITC)-conjugated donkey anti-rabbit and (B,E) fluorescein isothiocyanate (FITC)-conjugated donkey anti-mouse. Positions of the cell nuclei were detected by staining with Hoechst 33342. Scale bars: 60 μm.