A novel and rapid method to quantify Treg mediated suppression of CD4 T cells.

Measuring regulatory T cell suppression provides important insight into T cell dysfunction in autoimmune disease. However, to date, suppression assays are limited by the requirement for freshly isolated cells, and significant cell numbers. Here, we present a novel and rapid in vitro assay using effector T cell surface expression of both CD25 and CD134 as a surrogate marker of regulatory T cell-mediated suppression. This surface marker-based suppression assay works for frozen samples and for samples with limited cell numbers. It is also shorter taking two days to complete compared to the four days required for proliferation-based assays. Furthermore, this assay works with both in vitro expanded and natural Tregs, as well as anti-CD3/anti-CD28 bead-based and APC stimulation conditions. In conclusion, we have developed and validated a new suppression assay for cryopreserved samples with limited cell numbers that may be helpful to investigate T cell regulation in the context of infection or autoimmune diseases.