Plasma cells

Plasma cells are terminally differentiated B cells that have lost expression of B-cell surface markers including BCR-associated CD79 and gained high-level expression of the transcription factors Blimp-1 and IRF4, which drive the factory-like production of secreted antibodies. Long-lived plasma cells occupy specialised survival niches in the bone marrow, sustained by CXCL12/CXCR4 signals, APRIL, and BAFF from stromal cells, and can produce antigen-specific antibodies for decades without re-stimulation. With aging, these bone marrow niches become occupied by long-lived plasma cells from earlier infections and vaccinations, limiting space for newly generated cells — a mechanism contributing to the diminished durability of vaccine responses in elderly individuals, alongside the upstream germinal centre defects of B-cell senescence.