TNFSF13B and B-cell chronic lymphocytic leukemia: However, i.p. treatment with a neutralizing anti-APRIL antibody did not affect the proportion and absolute numbers of CLL cells in the peritoneal cavity of TCL1-Tg BAFF-/- mice, eliminating APRIL as a significant factor in maintaining the peritoneal CLL compartment in TCL1-Tg BAFF-/- mice (Supplementary Figure 4A, B).