CD5 expression in human B-cell populations

The origin of CD5+ B cells remains controversial. The differential response to ligation of CD5 resulting in apoptosis or proliferation provides insight into its roles in distinct human B cells. Here, Pierre Youinou, Christophe Jamin and Peter Lydyard review current knowledge of B-1 and B-2 cells, and propose that CD5 has different functions when expressed by different B-cell subpopulations.