TFRC and Autoimmunity: Furthermore, the low frequencies of Treg may likewise affect “Regulatory Follicular T cells” (Tfr) that specifically regulate Tfh activity, B cell activation and GC reactions (55, 73–75), further increasing the susceptibility to the development of autoimmunity in PIRD patients, as an imbalance between Tfh and Tfr has been associated with autoimmune diseases (76, 77).