B cell

B cell, one of the two types of lymphocytes (the other is the T cells). Similar to all lymphocytes, which are a kind of white blood cell, B cells begin as hematopoietic stem cells (HSCs), developing in the bone marrow.

B cells are involved in so-called humoral immunity, in which the body uses antibodies to fight off infectious agents. Each B cell has receptors on its surface that recognize antigens, which are proteins, polysaccharides, or other macromolecules that the immune system considers foreign (or “non-self”). When a B cell detects a specific antigen, it undergoes activation and clonal expansion, meaning that it generates many cells with the same antigen specificity.

Some activated B cells differentiate into plasma cells, which secrete antibodies. Antibodies produced by plasma cells are closely modeled after receptors on precursor B cells. Following their release into the blood and lymph, they bind to the target antigen and initiate its neutralization or destruction. Antibody production continues for several days or months, until the antigen has been overcome.

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lymphocyte: Types and functions of lymphocytes

Other activated B cells differentiate into memory B cells, which provide the immune system with long-lasting protection. If the immune system encounters the same antigen again, memory B cells help generate a faster and often stronger antibody response. This long-lasting immunological memory is one of the principles underlying vaccination.