Multiparameter flow cytometric detection of IL-21 and IL-17 in circulating CD4+ T-cells in patients with granulomatosis with polyangiitis (GPA) and healthy controls (HCs). Whole blood from GPA patients and HCs was stimulated with phorbol myristate acetate (PMA)/Ca-ionophore and analyzed for intracellular IL-21 and IL-17 cytokine expression. Representative fluorescence-activated cell sorting (FACS)plots of IL-21 versus IL-17 expression in stimulated CD4+ T-cells from a GPA patient (right plot) and an age- and sex-matched HC (left plot) (A). Value in each gate represents the percentages of cytokine producing cells. Percentages of total IL-21-producing Th-cells in peripheral blood of GPA patients (n = 42) and HCs (n = 29) (B). Percentages of circulating IL-21+IL-17-, IL-21+IL-17+, and IL-21-IL-17+ cells within the CD4+ T-cells in all GPA patients and HCs (C-E), or in antineutrophil cytoplasmic antibody(ANCA)-positive (n = 23) and ANCA-negative (n = 19) GPA patients (F-H). Horizontal lines represent the median percentage. P-values were calculated using the nonparametric Mann-Whitney U-test. *P < 0.05; ***P < 0.0005.
Abdulahad et al. Arthritis Research & Therapy 2013 15:R70 doi:10.1186/ar4247