TMV increase suppressor activity of Treg.

The FLOCA was used to simultaneously measure suppression proliferation of CFSE-labeled autologous CD4⁺CD25^neg RC and their apoptosis upon co-incubation with CFSE-negative Treg. RC cells stimulated with OKT3, anti-CD28 mAb and IL-2 (150 IU/mL) were co-cultured for 5 d with Treg pre-incubated or not with TMV. At harvest, cells were stained with 7-AAD and examined by flow cytometry. The suppressor assays were performed at the S:RC ratio of 1∶1. Treg pre-incubated with TMV induced higher levels of apoptosis (A) and greater inhibition of RC proliferation (B). The data are from one experiment of five performed. When Treg were pretreated with Concanamycin A or GrB inhibitor I and then incubated with TMV, the frequency of 7-AAD⁺ RC was lower (C) as was RC proliferation inhibition (D). Treg pretreated with FasL Ab and then incubated with TMV induced RC death (C) and inhibited RC proliferation (D).