Increased percentages of CCR4+ and CCR6+ memory T cell subsets in patients with granulomatosis with polyangiitis (GPA). Percentages of CD4+CCR4+ (a) and CD4+CCR6+ (b) T cells in the CCR7+CD45RA- central memory (TCM), CCR7-CD45RA- effector memory (TEM), CCR7+CD45RA+ 'naïve by definition' (TN), and CCR7-CD45RA+ 'revertant' effector memory (TEMRA) populations. (c) Dissection of the CD4+CCR7+CD45RA+ population with regard to CD45RA fluorescence intensity into CCR7+CD45RAhigh cells representing genuine TN and CCR7+CD45RAmed cells reminiscent of very early memory T cells (TVEM). Percentages of CCR4+ and CCR6+ cells in the CCR7+CD45RAmed and CCR7+CD45RAhigh subsets are shown. (d) Representative quadrant dot-plot analysis showing segregation of the gated CD4+CCR7+CD45RA+ T cell population into two subsets. CCR7+CD45RAmed T cells displayed CCR4 and CCR6 expression (TVEM). CCR7+CD45RAhigh T cells lacked CCR4 and CCR6 expression (genuine TN). Numbers in quadrants and histograms represent percentages of cells. Percentages of positive cells were assessed by flow cytometry. Values are presented as mean ± standard error of the mean. *P < 0.05, ***P < 0.001, Mann-Whitney U test. CCR, CC chemokine receptor; HC, healthy control.