CD40LG and immune system disorder: In patients with immunodeficiencies that are expected to impair GC responses (e.g., HIGM1), CD27brightIgM+IgD+ B cells were missing, but CD27dullIgM+IgD+ B cells were present, leading the authors to conclude that the CD27dullIgM+IgD+ B cells can be generated in a GC independent way, whereas CD27brightIgM+IgD+ B cells are post–GC memory B cells (65).