Plazmasejtek

Plazmasejtek, or plasma cells, are mature B lymphocytes that specialize in producing antibodies as part of the humoral branch of the adaptive immune system. They arise when B cells encounter an antigen and receive help from T cells, differentiating first into plasmablasts and eventually becoming long-lived plasma cells that reside mainly in the bone marrow and in mucosal tissues during ongoing immune responses.

Morphologically, plasma cells are characterized by an eccentric nucleus with a clock-face appearance, abundant basophilic cytoplasm rich in rough endoplasmic reticulum, and a prominent perinuclear Golgi apparatus. They typically lose surface immunoglobulin expression as they mature and express surface markers such as CD38 and CD138 (syndecan-1). They continue to synthesize and secrete large quantities of immunoglobulins (antibodies) of various isotypes, which neutralize pathogens, promote opsonization, and activate the complement system.

Distribution and life cycle vary with immune status. While many plasma cells are short-lived plasmablasts generated during a response, others become long-lived plasma cells that migrate to and persist in the bone marrow, sustaining antibody levels over time.

Clinical relevance includes plasma cell dyscrasias, most notably multiple myeloma, where a clonal proliferation of plasma cells accumulates in the bone marrow and leads to anemia, bone lesions, hypercalcemia, and renal impairment. Diagnostic approaches involve serum protein electrophoresis, immunofixation, free light-chain assays, and bone marrow biopsy to detect clonal plasma cells and monoclonal immunoglobulins.