Where are mature B and T cells found?
B cell activation occurs in the secondary lymphoid organs (SLOs), such as the spleen and lymph nodes. After B cells mature in the bone marrow, they migrate through the blood to SLOs, which receive a constant supply of antigen through circulating lymph.
T cells originate in the bone marrow and mature in the thymus. In the thymus, T cells multiply and differentiate into helper, regulatory, or cytotoxic T cells or become memory T cells.
- T cells are produced in the bone marrow and later move to the thymus where they mature. Helper T cells are the major driving force and the main regulators of the immune defense. Their primary task is to activate B cells and killer T cells. However, the helper T cells themselves must be activated.
- There are two types of adaptive immune responses: humoral immunity, mediated by antibodies produced by B lymphocytes, and cell-mediated immunity, mediated by T lymphocytes. The illustration below is divided into the main components of the innate and adaptive immune systems.
- Both cells are made in the Bone marrow and only the B - Lymphocytes mature in the Bone marrow, whereas the T Lymphocytes travel to the Thymus gland where they mature.
Lymphoid progenitors which have developed from hematopoietic stem cells in the bone marrow migrate to the thymus to complete their antigen-independent maturation into functional T cells . In the thymus, T cells develop their specific T cell markers, including TCR, CD3, CD4 or CD8, and CD2.
- NK cells provide rapid responses to viral-infected cells, acting at around 3 days after infection, and respond to tumor formation. Typically, immune cells detect major histocompatibility complex (MHC) presented on infected cell surfaces, triggering cytokine release, causing lysis or apoptosis.
- Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
- The T-cell receptor, or TCR, is a molecule found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules.
T cells can be distinguished from other lymphocytes, such as B cells and natural killer cells, by the presence of a T-cell receptor on the cell surface. They are called T cells because they mature in the thymus from thymocytes (although some also mature in the tonsils).
- Antigen-specific memory T cells located in the peripheral tissue are the first to respond to an invading pathogen such as a virus. After antigen recognition, these tissue-resident memory T cells can proliferate and generate a secondary effector T-cell response.
- An important difference between T-cells and B-cells is that B-cells can connect to antigens right on the surface of the invading virus or bacteria. This is different from T-cells, which can only connect to virus antigens on the outside of infected cells.
- Lymphocytes are produced by precursor cells in the bone marrow. They are found traveling in the blood stream, at sites of infection in large numbers, and in the lymph nodes which are located in the groin area, armpit area, and tonsils. There are also lymphocytes in the appendix and spleen.
Updated: 12th November 2019