APOA1 and common variable immunodeficiency: In the study by Macpherson et al., it was shown that monocyte-derived macrophages from CVID patients had impaired cholesterol efflux capacity along with decreased expression ATP-binding cassette transporter A1 (ABCA1), a cell membrane protein that exports excess cholesterol from cells to ApoA-I, in their PBMC, suggesting impaired reverse cholesterol transport (40).