Clonal expansion in B-CLL: fungal drivers or self-service?

Relatively few cancers arise in mature, differentiated cells. The propensity of mature B cells to transform has been linked to their longevity and proliferative potential, and stimulation of the B cell receptor (BCR) by cognate antigen may promote the transformation process. A study in this issue (Hoogeboom et al.) lends support to this notion, showing that cancer cells from a subset of patients with chronic lymphocytic leukemia (CLL) express a BCR specific for a sugar expressed by commensal yeast species. Another study, in contrast, suggests that B-CLL cells uniquely acquire the ability to signal in the complete absence of ligand.