Fine‐tuning of antigen‐specific immune responses by regulatory T cells activated via antigen recognition–independent and humoral factor–dependent mechanisms

CD4+ CD25+ Foxp3+ regulatory T cells (Tregs) are highly sensitive to IL-2, one of the many cytokines produced during immune responses, for their development, survival and functions. Although effects IL-2 administration on Tregs in vivo well characterized, elicited by an response have not been elucidated. Hence, this study, Treg behaviour IL-2–producing responses was explored using vitro murine systems. The use mixed lymphocyte culture (MLC) revealed that a large proportion increased size, accompanied both cell death proliferation status. Further, these Tregs, which were found recognize specific antigens, observed MLCs as being functionally activated various cytokines, including antigen-specific cells. This ‘bystander activation’ also mice with graft-versus-host reactions (GvHRs). Alternatively, effector from Treg-depleted exhibited lower or higher cross-reactivity compared control Tregs. Taken together, results suggest mainly released antigen. Subsequently, bystander contribute fine-tuning responses.