Bsejt
Bsejt, or B cell, is a lymphocyte central to the adaptive immune system. B cells surveil the body for foreign antigens and primarily defend through antibody production. They originate from hematopoietic stem cells in the bone marrow, where they rearrange immunoglobulin genes to form a unique B cell receptor (BCR). During maturation they pass through pro-B, pre-B, and immature stages to become mature naive B cells expressing surface immunoglobulin and requiring signaling cues from bone marrow and peripheral tissues to complete development.
When the BCR engages its antigen, Bsejt internalizes and presents fragments on MHC class II, enabling helper
Bsejt subsets include conventional B2 cells, B1 cells producing natural antibodies, and marginal zone B cells
Clinical relevance: B sejt defects cause hypogammaglobulinemia and susceptibility to infection. Bsejt–related cancers, such as lymphomas