Immune Cells Profiling in ANCA-Associated Vasculitis Patients—Relation to Disease Activity

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of necrotizing multiorgan autoimmune vasculitides that predominantly affect small blood vessels and are associated with the presence of ANCAs. The aim was to assess regulatory and effector cell populations accompanied by the suPAR biomarker level and link the so-defined immune state to the AAV disease activity. The research involved a multicomponent description of an immune state encompassing a range of B and T cell subsets such as transitional/regulatory B cells (CD19(+)CD24(++)CD38(++)), naïve B cells (CD19(+)CD24(INT)CD38(INT)), Th17 cells, T regulatory cells (CD4(+)CD25(+)FoxP3(+)) and cytotoxic CD4(+)CD28(−) cells by flow cytometry. The suPAR plasma level was measured by ELISA. The results indicate that AAV is associated with an increased suPAR plasma level and immune fingerprint characterized by an expansion of Th17 cells and T cells lacking the costimulatory molecule CD28, accompanied by a decrease of regulatory populations (Tregs and transitional B cells) and NK cells. Decreased numbers of regulatory T cells and transitional B cells were shown to be linked to activation of the AAV disease while the increased suPAR plasma level—to AAV-related deterioration of kidney function. The observed immune fingerprint might be a reflection of peripheral tolerance failure responsible for development and progression of ANCA-associated vasculitides.