# Plasma cells

Plasma cells are fully matured B cells, the body's antibody factories. They drop their B-cell surface markers (including CD79, which partners the B-cell receptor) and ramp up two master proteins, Blimp-1 and IRF4, that drive nonstop antibody output. Long-lived plasma cells settle into special survival niches in your bone marrow. Signals there, CXCL12/CXCR4, APRIL, and BAFF from support cells, keep them alive. They can pump out antigen-specific antibodies for decades, with no fresh trigger. With age, these niches fill up with long-lived plasma cells from old infections and vaccines. That leaves less room for newly made cells. It is one reason vaccine responses last less well in older people, alongside the upstream germinal-center defects of B-cell senescence.

## Sources

- Slifka MK, Antia R, Whitmire JK, Ahmed R. (1998). Humoral Immunity Due to Long-Lived Plasma Cells. Immunity. https://doi.org/10.1016/s1074-7613(00)80541-5

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_Canonical: https://longevity-austria.com/en/glossary/plasma-cells · Part of Longevity Cities · Updated 2026-06-22_