T-Bet IgM Memory Cells Generate Multi-lineage Effector B Cells.

Immunoglobulin M (IgM) memory cells undergo differentiation in germinal centers following antigen challenge, but the full effector cell potential of these cells is unknown. We monitored the differentiation of enhanced yellow fluorescent protein (eYFP)-labeled CD11c and CD11c T-bet IgM memory cells after their transfer into naive recipient mice. Following challenge infection, many memory cells differentiated into IgM-producing plasmablasts.

CD11c+ T-bet+ memory B cells: Immune maintenance during chronic infection and inflammation?

CD11c+ T-bet+ B cells have now been detected and characterized in different experimental and clinical settings, in both mice and humans. Whether such cells are monolithic, or define subsets of B cells with different functions is not yet known. Our studies have identified CD11c+ IgM+ CD19 splenic IgM memory B cells that appear at approximately three weeks post-ehrlichial infection, and persist indefinitely, during low-level chronic infection.

Early derivation of IgM memory cells and bone marrow plasmablasts.

IgM memory cells are recognized as an important component of B cell memory in mice and humans. Our studies of B cells elicited in response to ehrlichial infection identified a population of CD11c-positive IgM memory cells, and an IgM bone marrow antibody-secreting cell population. The origin of these cells was unknown, although an early T-independent spleen CD11c- and T-bet-positive IgM plasmablast population precedes both, suggesting a linear relationship.