This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 12. CD49c, CD72, and CD80. B cells may also express class II MHC and a variety of other CD not specific to B cells.
B cells appear to develop in a series of programmed steps.
Ag is not known to play a role in driving this sequence, but the interaction of immature B cells with Ag can lead to clonal inactivation or tolerance. Immature B cells that are not inactivated may continue to develop into mature naive B cells and leave the marrow to enter peripheral lymphoid organs. There, interaction between sIgG and foreign Ag converts them into lymphoblasts. Terminally differentiated, these B cells become plasma cells, which secrete Ig of a single class. B cells in peripheral tissues are precommitted to respond to a limited number of Ags.