The enhanced state of T cell activation and effector function in CVID may further contribute to the B cell hyperplasia observed in CVID ILD due to a lack of T cell-mediated regulation of B cell activity in addition to upregulation of non-canonical NF-κB signaling in B cells as a result of more widespread stimulation of CD40 through CD40L expressed on activated T cells (113, 114). Here, CD40 is linked to common variable immunodeficiency.