When peritoneal TCL1-Tg BAFF-R-/- CLL cells were injected i.v. into WT or BAFF-/- recipient mice, BAFF-R-/- CLL cells were detected in the peritoneal cavity but their proportions were significantly reduced in the spleen and blood of both BAFF-/- and WT recipient mice (Figure 5C). This evidence concerns the gene TNFSF13B and B-cell chronic lymphocytic leukemia.