Dendritic cells associated with plasmablast survival.

A subset of myeloid dendritic cells is described which is associated with the ability of splenic and lymph node plasmablasts to survive and differentiate into plasma cells. Plasmablast-associated dendritic cells (PDC) are CD11c(high), DEC-205(-) and unlike conventional dendritic cells do not associate with T cells. The following findings suggest a requirement for PDC if plasmablasts are to differentiate to plasma cells. First, when large numbers of B cells are recruited into antibody responses and plasmablasts outgrow the PDC stroma, only those associated with PDC survive and differentiate into plasma cells. Conversely, if the number of PDC is increased by ligating their CD40, more plasmablasts survive on the expanded PDC stroma and differentiate into plasma cells. Finally, in T cell-deficient mice, the plasma cells that develop atypically in the T zones in response to thymus-independent antigens are associated with ectopic PDC.