B-1 cells: orthodox or conformist?

B-1 cells differ from conventional peripheral B cells (B-2) by anatomical l ocation, surface marker expression, antibody repertoire and growth properti es. The lineage hypothesis of B-1 cell development attributes the propertie s of B-1 cells to their unique origin. The induced differentiation hypothes is suggests the surface-immunoglobulin-driven development of B-1 cells from common B-1/B-2 cell progenitors, In both models self-antigen-induced signa lling plays the central role in positive selection of B-1 cells, The abilit y of B-1 cells to be positively selected by self-antigens raises questions about the mechanism of this phenomenon.