TFRC and in situ carcinoma: Although ours is the first study to examine the Helios expression in CIS/MS in comparison to HC, these initial results support the notion that impaired Helios expression may contribute to MS pathogenesis via diminished Treg- and Tfr-suppressive function, dysregulation of Tfh and GC reactions and subsequent development of autoreactive effector cells and ectopic GC-like structures, as have been detected in MS.19, 20 Furthermore, the detection of impaired Helios expression from the earliest stages of MS may indicate an underlying role of Helios in disease pathogenesis.