TNFSF13B and common variable immunodeficiency: ELISAs of BAL fluids of 30 CVID patients and 25 healthy donors revealed an increased concentration of APRIL in BALF of CVID patients when compared to healthy donors (Figure 4A) while BAFF, CXCL9, CXCL13, CXCL14, and CXCL10 (IP10) of the same samples were below the detection limit (data not shown).