Long-lived plasma cell

Long-lived plasma cells (LLPCs) are a distinct subset of plasma cells that play a crucial role in maintaining humoral memory and long-term immunity. They continuously produce and secrete high-affinity antibodies into the bloodstream, conversely to memory B cells, which are quiescent and respond quickly to antigens upon recall.

Initially, it was believed that memory B cells replenish LLPCs. However, allergen-specific Immunoglobulin E (IgE) production through bone marrow transplantation in non-allergic individuals suggests LLPCs may be long-lived because the allergies developed without antigenic re-stimulation. That led to the understanding that LLPCs are long-lived cells that contribute to the sustained production of specific antibodies.