CD4 and common variable immunodeficiency: In vitro and in vivo experiments showed similar effects of IVIg on DC: the addition in vitro of IVIg at a concentration of 10 mg/ml to DC cultures of CVID patients partially restored the defective markers of differentiation (CD1a) and co-stimulation (CD80, CD86, and CD40) (26); a recent in vivo study in CVID demonstrated that after 6–12 months from initiation of replacement, IVIg therapy partially restored the reduced frequency of mDC, the altered expression of their co-stimulatory molecules and the CD4 T cell count (27).