T cells of patients with CVID, in particular CD8 T cells, exhibit high levels of activation and memory markers including CD29, CD38, CD95, CD45RO and Human leukocyte antigen (HLA)-DR, and low expression of CD27, CD62L and CD45RA.23–26 Although the expansion of T-cell memory is natural with advancing age, this process is greatly enhanced in CVID. Here, CD27 is linked to common variable immunodeficiency.