CX3CR1 and common variable immunodeficiency: Besides, the percentage of monocytes expressing CX3CR1, another specific marker for CD16+ monoytes [51], was also significantly reduced in the peripheral blood of IVIg-treated CVID patients (Supplementary Fig. 1B), suggesting that the decrease in CD16+ monocytes in IVIg-treated CVID patients reflects changes in monocyte subsets proportions and is not merely due to IVIg-mediated occupancy or internalization of CD16.