B-cell

Overview
  • B-cells are a subtype of lymphocyte which synthesize Antibody and are the major effector cells of Humoral Immunity. The development of these leukocytes occurs largely within the bone marrow and the final steps of differentiation occur in the spleen.
Function
  • The major function of B-cells is to synthesize Antibody molecules which bind with high specificity and affinity to microbial antigens. The function of antibody is discussed further in its own page; briefly, binding of antibody to microbes can either directly inhibit microbial function or causes recruitment of other immune effector cells to kill the bacteria. Consequently, B-cells are critical for immunity to extracellular pathogens.
Subtypes
  • B-cells go through a variety of stages during their development which is discussed in B-cell Development. However, the major functionally important stages to be aware of are the final stages known as the Plasma Cell and Memory B Cell stages. Plasma Cells are B-cells specialized for high levels of antibody synthesis and secretion. Memory B Cells are quiescent antigen-sepecific cells which differentiate following a primary immune response to a particular microbe which can become rapidly activated to differentiate into Plasma Cells if the microbe if re-encountered. B-cells can also be classified based on the subtype of antibody which they secrete.
Development
Morphology
  • B-cells, like all lymphocytes possess a large, unlobulated nucleus, justifying their classification as Mononuclear Cells. The nuclei of lymphocytes generally takes up the majority of the cell and thus they possess little in the way of cytoplasm