Cells and organs of immune system Cells and organs of immune system Presented by Yogesh kumar [M.sc. Bioinformatics 1st sem] Bioinformatics]
The immune system is an organization of molecules, cells, tissues, and organ with specialized role in defending against viruses, microorganisms, cancer cells, and nonself proteins.The cells involved in the immune reaction are organized into tissue and organs which are collectively refer as lymphoid system. This system perform the major function of protecting the body against the various microorganisms that enter the body through all the possible routes. It is formed of lymphoid cells and lymphoid organs.
They have specific name in the body as depending on their location
T cell B cells. Originate from bone marrow . Originate and mature in and mature in thymus bone marrow. They can’t function without . They can functions due to MHC molecules presence of antibody. They are differentiate into TH . They are not and Tc. They have CD8 markers . They have CD4 markers. They secrete cytokines . They do lysis of the virus-infected cell
Primary lymphoid organs..are the major site of lymphopoiesis . Here the lymphoid stem cells proliferate, differentiate and mature into immunocompetent cells in the absence of antigenic stimulation. The Thymus and the bursa of fabricius (in birds) are the primary lymphoid organs.THYMUS Blobbed Organ on Top of Heart Reaches Max. Size During Puberty in 10 year of age › 70g infants, 3 g in adults 95-99% Of T Cells Die in Thymus › self reactivity or no reactivity to Ag Consists of Cortex and Medulla
In birds, undifferentiated lymphocytes move from the bone marrow to the bursa of Fabricius where B cells mature. In mammals, the bone marrow is the site of B-cell maturation. Like thymic selection during T-cell maturation, a selection process within the bone marrow eliminates B cells with self-reactive antibody receptors (the acquisition of tolerance).
The secondary lymphoid organs include the well organized, encapsulated spleen and lymph nodes.The spleen is the larger secondary lymphoid organ located in the abdominal cavity. where lymph node specialize for trapping micro organism and antigens from local tissues, the spleen specializes in filtering the blood and trapping blood borne microorganism and antigens. once trapped by macrophage and dendritic cells, the pathogen is phagocytosed and antigens are presented to b and T cells, which become activated to carry out their immune functions.
Lymph node..lies at the junction of lymphatic vessels where they filter out harmful microorganism and antigen from the lymph pathogens and antigens are trapped by phagocytic and dendritic cells. Fixed macrophages and then phagocyte the foreign material. It is with in lymph node that B cells proliferate into antibody secreting plasma cells