Plasma cell

A plasma cell is the terminal differentiated form of a B cell, specialized for the high-volume secretion of antibodies. A single plasma cell can produce thousands of antibody molecules per second, making it the primary effector of humoral immunity. This extraordinary synthetic output comes at a cost: plasma cells have sacrificed the proliferative capacity and receptor plasticity of their B-cell precursors, committing to a single antibody specificity for the remainder of their lifespan.

Plasma cells are not uniform. Short-lived plasma cells emerge early in immune responses and provide immediate antibody production, while long-lived plasma cells migrate to survival niches in the bone marrow, where they can persist for years as a continuous source of protective antibodies. The factors that determine which B cells become short-lived versus long-lived plasma cells — and which survival signals maintain the long-lived population — are active areas of research with direct relevance to vaccine durability and multiple myeloma.