CXCL12 and common variable immunodeficiency: As LSCs are involved in shaping the GC compartment by the secretion of chemokines (CXCL12, CXCL13, CCL19, CCL21), survival factors (IL-7, RANKL), the generation of reticular conduits and the presentation of antigen (CR1, CR2 expression by FDCs), we hypothesize that an impaired interaction between lymphocytes and LSCs in CVID patients may contribute to the altered GC’s polarization and microenvironment and therefore result in the poor GC output in some of the patients.