TLR9 and common variable immunodeficiency: However, defective TLR7 and TLR9 signaling in B cells and plasmacytoid dendritic cells (pDCs), deficient IFN-α secretion, and impaired B cell function alter innate immune responses in CVID, thus preventing TLR-mediated enhancement of humoral immunity in vivo and possibly increasing susceptibility to enteroviral and rhinoviral infections [6, 7].