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Abstract: TH-PO552

In Vitro Expansion of Regulatory T Cells Restores Functional Capacity in ANCA Vasculitis

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: From Inflammation to Fibrosis

Authors

  • Free, Meghan E., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Elmore, Sandra H., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Ciavatta, Dominic J., The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Falk, Ronald, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
Background

ANCA vasculitis is an autoimmune disease characterized by loss of tolerance to one of two main ANCA autoantigens, myeloperoxidase or proteinase 3. Broad immune system dysfunction is exhibited within relapses of disease which includes regulatory T cell (Treg) dysfunction. Previously, our group and others have demonstrated that Tregs are functionally deficient and unable to restrain effector T cell proliferation and cytokine production in ANCA vasculitis.

Methods

Tregs defined as CD4+, CD127low, CD25high, and CD45RA+ were sterile sorted from cryopreserved peripheral blood mononuclear cells. Sorted Tregs were then expanded in vitro with combinations of supplemental IL-2 and stimulation from CD3/CD28 Dynabeads for 14 days. After the 14 day expansion, Tregs were analyzed for phenotype and function was assessed by in vitro suppression assays.

Results

After 14 day expansion, Tregs from both healthy controls and patients with ANCA vasculitis expanded between 500-2000 fold over day 0 starting material. Expanded Tregs maintained >95% FOXP3+ protein expression and surface markers of CD25high, CD127low. Healthy control Tregs had potent suppressive capacity with >90% suppression of effector T cells. Expanded Tregs from ANCA vasculitis patients varied in their suppressive capacity from 30% suppression to >60% suppression of effector T cells. Variances in degrees of suppression may be due to clinical activity status and/or medication regimen at time of sample.

Conclusion

Tregs taken directly ex vivo from ANCA vasculitis patients fail to suppress effector T cell function. We have utilized a Treg expansion protocol that yields highly pure Tregs with 500-2000 fold expansion of numbers of Treg cells. Importantly, these expanded Tregs are functionally able to suppress autologous and allogeneic effector T cell proliferation. These studies are foundational for future trials of Treg expansion to maintain remission in ANCA vasculitis.

Funding

  • NIDDK Support