B Cells - Overview



B-cells are lymphocytes which produce antibodies, mediating humoral immunity. B-cells can be identified by their expression of CD19 and CD20, surface markers that also serve as drug targets in B-cell mediated diseases. B-cells originate and mature in the bone marrow and later migrate to lymphoid tissues, where they reside to wait for antigens. Once activated against an antigen, B-cells mediate the humoral immune response by producing antibodies.

Key Points

  • B Cells
    • Lymphocytes of the adaptive immune system
      • Must be activated against a specific antigen
    • Mediate humoral immunity (make antibodies)
    • Express CD19 and CD20
      • CD20 is important as drug target of Rituximab
    • Originate from and mature in the bone marrow
    • Migrate to and reside in lymphoid tissue
      • e.g. follicles of lymph nodes, white pulp of spleen, unencapsulated lymphoid tissue
    • After B-Cell Activation by an antigen, they differentiate into: