Assessment of suppressive capacity by human regulatory T cells using a reproducible, bi-directional CFSE-based in vitro assay.

Regulatory T cells are involved in the maintenance of tolerance. Alterations in their functional capacity are implicated in the development of autoimmunity. In the case of common autoimmune disorders the defects in suppression may be partial, and may be due to a loss of Treg function, or a resistance to suppression by responder T cells. Thus in order to assess Treg function, an in vitro assay that is sensitive enough to demonstrate modest alterations in suppression, and which can differentiate between impaired suppression due to Treg dysfunction, and responder cell resistance is ideal. In this chapter we describe a CFSE based proliferation assay that utilizes a bead based activation system, which is reproducible, consistent and able to distinguish between defects in Treg function and the resistance of responder T cells.