T follicular regulatory cells, or Tfr cells, express the germinal center (GC)-defining transcription factor Bcl6, and migrate to the B-cell follicle following immunization and infection, adding to the complexity of interplay between different cell types within the B cell follicle and GC and the heterogeneity of Treg cells that express T helper (Th) cell transcription factors (13–18). The gene discussed is TFRC; the disease is infection.