Bsejtek

Bsejtek are a type of lymphocyte that forms part of the adaptive immune system. They circulate in the blood and reside in lymphoid organs, where they coordinate antibody-mediated (humoral) immunity. Each Bsejt expresses a membrane-bound receptor, the B-cell receptor (BCR), which recognizes specific antigens. In mammals, Bsejtek originate from hematopoietic stem cells in the bone marrow and mature through stages that produce a diverse repertoire capable of recognizing many pathogens.

Upon encountering their specific antigen, typically with help from activated helper T cells, Bsejtek become activated. Activation involves signals through the BCR and co-stimulatory molecules such as CD40, as well as cytokines. Activated Bsejtek proliferate and differentiate into plasma cells, which secrete large quantities of antibodies, and into memory Bsejtek, which persist long-term to provide rapid responses upon re-exposure. In germinal centers of lymphoid tissues, Bsejtek undergo somatic hypermutation and class switch recombination, increasing antibody affinity and diversifying effector functions.

Antibodies produced by plasma cells can neutralize pathogens, promote their clearance by phagocytes, and activate the complement system. Bsejtek can also present antigen to helper T cells via MHC class II molecules, reinforcing the interaction between humoral and cellular immunity.

Clinical relevance: deficiencies or dysregulation of Bsejtek function can lead to increased infection risk, autoimmune disease, or B cell cancers such as leukemias and lymphomas. Vaccination relies on Bsejtek to generate durable antibody-mediated immunity and memory, forming a cornerstone of protective responses.