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The key difference between T Cells and B Cells is that T Cells are involved in the cell-mediated immunity (CMI), but B cells are involved in antibody-mediated immunity (AMI) or humoral-mediated immunity.
T Cells Vs. B Cells
Our body has a self-defense system known as the immune system. When any foreign body or particles like bacteria virus etc. attacks on the body, immune system activated and started acting against a foreign invader. There are different types of cells in the immune system that play their role in removing harmful particles from the body like macrophages, basophils, dendritic cells or neutrophils, etc. But, for a more sophisticated attack, It forms special T-cells and B-cells collectively known as lymphocytes. These are the special cells of the immune system that recognize special foreign threats and attack them. These two cells actually vary in their function. T cells recognize antigens, combat microorganisms and effect the rejection of foreign tissues in case of transplant, etc. and this type of response is called cell-mediated response while B cells recognize antigen and form antibodies against it and this type of response is known as a humoral immune response. T cells produced in bone marrow and mature in the thymus while B cells form in bone marrow and also mature there.
What are T Cells?
The name “T cells” is derived from Thymus, because these cells form in bone marrow but mature in Thymus in the neck. They play a vital role in cell-mediated response because they lack antigens on their surface and identify antigen outside the infected cell. There are three types of T cells, i.e., helper T cells, cytotoxic or “killer” T cells (memory T cells) and regulatory T cells. These cells after differentiation are sent to the bloodstream or lymphatic system and play a significant role in the removal of pathogens or any other invader. As any foreign particle like a virus, bacteria, etc. enter into the body, these cells become activated and perform a different function to suppress or remove that particle. Helper cells regulate many immunological processes like the maturation of B cells etc. and shows active immune response by secreting different proteins like cytokines etc. Cytotoxic or killer cells destroy virus-infected cells and tumor cells and also play a role in transplant rejection. These cells, later on, convert into the memory cells that remain active all the time to quickly response against invaders at any time. Regulatory cells play their role in controlling the immune system.
What are B Cells?
B cells derived its name from “Bursa of Fabricius” where they identify first in the birds while in mammals they form and mature in bone marrow. They protect the body by showing a cell-mediated response. They have surface antigens so; they can easily recognize the foreign particle and show direct response against it by producing antibodies. They are found in blood and as soon as come in contact with any invader, they divide into plasma cells and memory cells. Plasma cells make a specific type of antibody against the specific invader. It attacks the predator to destroy it and also act as a marker that helps the T cells to recognize the infected cells and destroy it. So, antibody-coated invaders become easy to recognize by other proteins of the immune system and quickly destroyed by them. It also causes the phagocytosis of harmful invaders. After the removal of the foreign particle, plasma cells disappear, but memory cells remain active for a long time to remove the invader immediately in the case of another attack. B cells do not act against cancer cells.
- T-cells are the lymphocytes that form the cell-mediated immune system (CMI) while В-cells show humoral or antibody-mediated immune system (AMI).
- T cells are also known as T lymphocytes whereas B cells are also known as B lymphocytes.
- T cells form in bone marrow but mature in the thymus, but B cells develop and mature in bone marrow in mammals and Bursa of Fabricius in birds.
- T Cells form 80% of lymphocytes while B cells form 20% of lymphocytes.
- Membrane receptors of the T cells are known as TCR while that of B cells are known as BCR.
- Surface antibodies are absent in T cells while present in B cells.
- T cell only connects to virus antigens on the outside of infected cells, but B cell connects to antigens right on the surface of the attacking virus or bacteria.
- T cells are distributed in Parafollicular areas of cortex in nodes and periarteriolar in spleen whereas B cells are distributed in germinal centers of lymph nodes, gut, spleen, respiratory tract and also in subcapsular and medullary cords of lymph nodes.
- T cells are divided into three types, e., helper, killer and regulatory cells while B cells form memory cells and plasma cells.
- T cells also act against cancer cells while B cells do not act against cancer cells.
- T cells have a long life span while B cells have a short life span.
From the above discussion, it is concluded that T cells are the lymphocytes that are formed in bone marrow but mature in the thymus. They are of three types, i.e., helper, killer and regulatory cells and show cell-mediated response against foreign invaders. Whereas, B cells are the lymphocytes that are form and mature in bone marrow in mammals and Bursa of Fabricius in birds. It is of two types, i.e., memory cells and plasma cells and form humoral or antibody-mediated immune system (AMI).