Table 2.

List of the different T follicular regulatory (Tfr) cell subsets and their putative functions.

Tfr cell subsets	Putative function	Reference
Tfr cells derived from thymic regulatory T cells	Maintain tolerance and restrain magnitude of GC B cells	(6–8)
Tfr derived from naïve Th cells	Mostly specific for the immunizing Ag allowing the control of Ag-specific B cell response through cognate interaction	(41)
IL10-producing Tfr cells	Promote plasmablast differentiation and GC development	(10)
PD-1+ Tfr cells in mouse and PD-1lo in human	Abundant population that displays less suppressive activity preventing excessive suppression of GC reaction	(61, 86)
PD-1+ Tfr cells in human	Display greater suppressive activity (TGFβhi, IL-10hi, CTLA-4hi)	(86)
Circulating Tfr cells	Display less suppressive capacity and home to GC upon recall contributing to faster memory T follicular helper cell response	(66)