CD27 and B-cell chronic lymphocytic leukemia: Although the cellular origin of CLL is still debated, several lines of evidence suggest that CLL cells are antigen-experienced,37 resembling memory B cells.38 Within this context, IGHV-mutated CLL cells, associated with favourable clinical prognosis and derived from the CD5+/CD27+ post-GC B-cell subset, could be similar to ‘classic memory B cells’ generated by a typical GC-based reaction, represented in our system as a CD27+ GC B cells (Figures 3a–c).