Memory B cell

In immunology, a memory B cell (MBC) is a type of B lymphocyte that forms part of the adaptive immune system. These cells develop within germinal centers of the secondary lymphoid organs. Memory B cells circulate in the blood stream in a quiescent state, sometimes for decades. Their function is to memorize the characteristics of the antigen that activated their parent B cell during initial infection such that if the memory B cell later encounters the same antigen, it triggers an accelerated and robust secondary immune response. Memory B cells have B cell receptors (BCRs) on their cell membrane, identical to the one on their parent cell, that allow them to recognize antigen and mount a specific antibody response.Maintenance of the B-cell memory compartment in blood has been associated with a lower risk of relapse in NSCLC treated with perioperative chemoimmunotherapy. In a T-cell dependent development pathway, naïve follicular B cells are activated by antigen-presenting follicular B helper T cells (TFH) during the initial infection, or primary immune response. Naïve B cells circulate through follicles in secondary lymphoid organs (i.e. spleen and lymph nodes) where they can be activated by a floating foreign peptide brought in through the lymph or by antigen presented by antigen-presenting cells (APCs) such as dendritic cells (DCs). B cells may also be activated by binding foreign antigen in the periphery where they then move into the secondary lymphoid organs. A signal transduced by the binding of the peptide to the B cell causes the cells to migrate to the edge of the follicle bordering the T cell area. The B cells internalize the foreign peptides, break them down, and express them on class II major histocompatibility complexes (MHCII), which are cell surface proteins.