plasmacyte

A plasmacyte, also known as a plasma cell or effector B cell, is a type of white blood cell that has been differentiated from a B lymphocyte. Plasmacytes are responsible for producing and secreting large quantities of antibodies. These antibodies are crucial components of the adaptive immune system, playing a vital role in neutralizing pathogens such as bacteria and viruses.

The differentiation of a B lymphocyte into a plasmacyte is a complex process triggered by the presence of an antigen. Upon encountering its specific antigen, a B cell proliferates and matures, eventually transforming into a plasmacyte. This transformation involves significant changes in cellular morphology and function. Plasmacytes are characterized by an abundant cytoplasm rich in ribosomes and endoplasmic reticulum, reflecting their high rate of protein synthesis and secretion. They typically have an eccentric nucleus, often with a clock-face appearance due to heterochromatin distribution.

Once differentiated, plasmacytes are short-lived cells, but their antibody production is essential for clearing infections and providing immunological memory. These antibodies bind to specific antigens on the surface of pathogens or toxins, marking them for destruction by other immune cells or neutralizing their harmful effects directly. In some cases, plasmacytes can persist for extended periods, contributing to long-term immunity. Abnormal proliferation of plasmacytes can lead to conditions like multiple myeloma, a type of blood cancer.