plasma cells

Plasma cells are B lymphocytes that have been activated to differentiate and mature by CD4+ helper T lymphocytes. Activated B cells become either memory B cells or plasma cells, which secrete copious amounts of monoclonal antibodies against the original antigen that triggered the antigen presenting cells.

Affinity maturation is a process of affinity-selected differentiation and maturation of activated B cells. Repeated exposures to the same antigen provokes greater antibody ligating affinity in the antibody secreted by successive generations of plasma cells. Isotype switching, in response to signaling by specific cytokines, provides for a switch of production from IgM to other Ig isotypes following first exposure to an antigen. T cell-produced immune cytokines, such as interleukin-4 (IL-4), interferon-γ (IFN-γ), and TGF-β effect isotype switching.

Plasma cells are predominantly located in the bone marrow (0.2% to 2.8% of leukocytes) and are rarely found in the peripheral blood.(description of morphology)

Plasma cells are seen in abnormal numbers in multiple myeloma, plasma cell leukemia, Waldenström's macroglobulinemia, and MGUS (monoclonal gammopathy of uncertain significance).

[] tem plasma cell [] micrograph macrophage surrounded by normal plasma cells [] micrograph macrophage & plasma cells []

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