FCRL4 and common variable immunodeficiency: For example, we detected protein downregulation of CD54 (ICAM1), CD86, CD80, CD70, CD71 and CD307d (FCRL4), together with protein upregulation of IgB (CD79B), CD196 (CCR6), CD45 (PTPRC), CD32 (FCGR2), CD19, and CD35 (CR1) in the activated memory B cells of the CVID patients compared with the healthy donors.