Figure 2.

Expression of ICOS on peripheral blood T cells from SLE patients and normal control individuals. Peripheral blood T cells were analyzed using three-colour staining (anti-CD4-PerCP or anti-CD8-PerCP, anti-CD45RO-PE, and biotinylated JTA009 plus streptavidin-FITC) and flow cytometry for ICOS expression. Representative patterns of ICOS expression on (a) CD4⁺CD45RO⁺ and (b) CD8⁺CD45RO⁺ peripheral blood T cells from a patients with active SLE are shown. The background histograms (shown in black) were obtained by staining with anti-CD4-PerCP or anti-CD8-PerCP, anti-CD45RO-PE, and biotinylated JMAb23 (control mAb) plus streptavidin-FITC. (c-f) Peripheral blood T cells from patients with active SLE (n = 16), patients with inactive SLE (n = 16) and normal control individuals (n = 16) were analyzed using three-color staining and flow cytometry for ICOS expression. Percentages of ICOS⁺ cells (panels c and d) and MFIs of ICOS⁺ cells (panels e and f) are shown. CD4⁺CD45RO⁺ (panels c and e) and CD8⁺CD45RO⁺ (panels d and f) peripheral blood T cells were analyzed. Bars indicate median values of each group. Percentages (medians) of CD4⁺CD45RO⁺ ICOS⁺ cells and CD8⁺CD45RO⁺ICOS⁺ cells, respectively, were as follows: active SLE, 71.3% and 33.2%; inactive SLE, 11.1% and 6.2%; and normal control individuals, 42.8% and 19.2%. The MFI (medians) of CD4⁺CD45RO⁺ ICOS⁺ cells and CD8⁺CD45RO⁺ICOS⁺ cells, respectively, were as follows: active SLE, 1.80 and 1.25; inactive SLE, 0.45 and 0.40; and normal control individuals, 1.10 and 0.50. *P < 0.05, **P < 0.01, and ***P < 0.005, by Mann-Whitney U-test. FITC, fluorescein isothiocyanate; ICOS, inducible co-stimulator; mAb, monoclonal antibody; MFI, mean fluorescence intensity; NC, normal control; PE, phycoerythrin; PerCP, peridinin chlorophyll protein; SLE, systemic lupus erythematosus.