Specific recognition and clearance of extracellular pathogens
B cells (bursa or bone marrow-derived cells) are a critical component of the adaptive immune response. B cells are defined by their expression of clonally diverse cell surface and secreted immunoglobulin B cell receptors (BCR) which bind specifically to antigenic epitopes. B cell development, defined by the expression of multiple cell surface markers including CD19, CD45R, and surface lgM, is initiated in the fetal liver before birth and in the bone marrow in adults; however subsequent functional maturation occurs in secondary lymphoid tissue.
B cells that have exited the bone marrow migrate to the spleen where they undergo further maturation via "transitional" stages identified by the expression of markers including CD21, CD23, CD24 and AA4.1 in the mouse, eventually reaching final maturation as "follicular" B cells. T-cell-dependent immune responses induce additional germinal center (GC) maturation in secondary lymphoid organs including class-switch recombination (CSR) and somatic hypermutation (SHM); both of these processes being dependent on the enzyme activation-induced cytidine deaminase (AID). Upon cross-linking of the B cell receptor (BCR), a signaling cascade is initiated that enables B cell effector activity. B cells in peripheral compartments may also belong to more specialized B cell subsets including CD5+ B1 cells or Marginal Zone (MZ) B cells. Germinal center maturation of B cells leads to the generation of memory B cells and the development of antibody-secreting plasma cells.
Aberrant B cell development can result in the transformation of B cells into a variety of leukemias or lymphomas with phenotypes resembling the developmental stage of the B cell prior to transformation. In addition to malignant transformation, B cells that are not properly tolerized to self, play a role in autoimmune conditions such as systemic lupus erythematosus (SLE) and rheumatoidarthritis (RA).
eBioscience offers a complete portfolio of reagents to study all aspects of B cell biology including their development, function and pathogenesis.