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How do lymphocytes develop from stem cells in bone marrow?
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immune system
Stimulation of immune response by activated helper T cells. Activated by complex interaction with molecules on the surface of a macrophage or some other antigen-presenting cell, a helper T cell proliferates into two general subtypes, TH1 and TH2. These in turn stimulate the complex pathways of the cell-mediated immune response and the humoral immune response, respectively.
All lymphocytes originate from stem cells located within the bone marrow. While all lymphocytes begin their development in this environment, their maturation pathways diverge based on their specific type:12
- B lymphocytes (B cells): These cells remain in the bone marrow to undergo maturation before being released into the bloodstream. Once in circulation, they may undergo further differentiation in secondary lymphoid tissues, such as the spleen or lymph nodes, particularly when stimulated by foreign antigens.12
- T lymphocytes (T cells): The precursors of T cells migrate from the bone marrow to the thymus. Within the thymus, they differentiate under the influence of hormonelike substances. After reaching maturity, these T cells exit the thymus and circulate through the blood to reach lymphoid tissues.12
This process of development is essential for establishing immunologic competence, allowing the body to recognize and respond to foreign substances.2