Abnormal Expression Pattern of the IL-2 Receptor β-Chain on CD4+ T Cells in ANCA-Associated Vasculitis

Abstract EN

Background/Aim.

ANCA-associated vasculitis (AAV) is a small-vessel vasculitis of autoimmune origin.

In addition to autoantibodies, T cells have a pivotal pathophysiological role in this disease.

T-cell homeostasis and immune tolerance critically depend on IL-2 and its receptor expressed by T cells.

In this study, we investigated the IL-2 receptor (IL-2r) expression on CD4+ T cells in AAV.

Methods.

Thirty patients with AAV and 15 age-matched healthy controls (HC) were enrolled.

T cells from peripheral blood were analysed by flow cytometry for expression of the IL-2r α- and β-chain.

Results.

The IL-2r α-chain was overexpressed in AAV as compared to HC (36±16% versus 20±9%, P<0.005).

The IL-2r-β-chain expression was significantly reduced on CD25+ CD4+ T-cells and CD4+CD25+FoxP3pos regulatory T-cells (Tregs; AAV versus HC: 48±14% versus 62±9%, P=0.002 and 38±18% versus 68±5%, P=0.002).

Low β-chain expression in AAV was associated with relapsing disease and systemic vasculitis with renal involvement.

Conclusion.

The IL-2r expression pattern is abnormal in AAV.

To our knowledge, we are the first to show that the β-chain expression is drastically diminished on T cells in AAV and related to a less favorable disease course.

Given the indispensable function of the β-chain in IL-2 signaling of T cells, diminished expression may contribute to disturbed immune homeostasis in AAV.