Figure 1. Expression of RANK-L on A. actinomycetemcomitans-reactive periodontal CD4⁺ T-cells detected by flow cytometry and PCR analyses. The left panel (FACS analysis of RANK-L expression on cell surface by immunostaining to OPG-FITC conjugates): (a) un-stimulated HuPBL-derived CD4⁺ T-cells as background control; (b) isotypic Ig control for background staining; (c) HuPBL-derived CD4⁺ T-cells activated by anti-h-ßTCR plus anti-CD28 Mabs as positive control for RANK-L expression; and (d) periodontal CD4⁺ T-cells stained with OPG-FITC for cell-surface expression of RANK-L. The right panel (RT-PCR by the use of specific primers for RANK-L): (1) A. actinomycetemcomitans (Aa)-reactive periodontal CD4⁺ T-cells from HuPBL-NOD/SCID mice which received HuPBL samples from one LJP subject (called LJP 2); (2) Aa-reactive periodontal CD4⁺ T-cells from HuPBL-NOD/SCID mice which received HuPBL samples from another LJP subject (called LJP 1); (3) naïve unstimulated HuPBL-derived CD4⁺ T-cells; and (4) HuPBL-derived CD4⁺ T-cells activated by anti-h-ßTCR plus anti-CD28 mAbs as positive control for RANK-L expression. The experimental procedures have been described previously (Teng et al., 2000; Teng, 2002).