Immunochemistry Lecture Notes PDF

IMMUNO CHEMISTRY MC 101 – LP - BIOCHEMISTRY Distinguish self from non-self. Explain how the body defends itself from invasion. Identify the organs and cells that make up the immune system. Describe the role of immunoglobulins; Describe the roles of T-Cells and T-Cell Receptors. Explain the signific...

IMMUNO CHEMISTRY MC 101 – LP - BIOCHEMISTRY Distinguish self from non-self. Explain how the body defends itself from invasion. Identify the organs and cells that make up the immune system. Describe the role of immunoglobulins; Describe the roles of T-Cells and T-Cell Receptors. Explain the significance of immunization. LEARNING OBJECTIVES Introduction Immune response is how our body recognize and defends itself against bacteria, viruses, and other substances that appears foreign and harmful. The immune system protects the body from possibly harmful substances by recognizing and responding to such substances called ANTIGENS. Self versus Non-Self The immune system has the capacity to distinguish between body cells (‘self’) and foreign materials (‘non-self’) - It will react to the presence of foreign materials with an immune response that eliminates the intruding material from the body. All nucleated cells of the body possess unique and distinctive surface molecules that identify it as self - These self markers are called major histocompatibility complex molecules (MHC class I) and function as identification tags - The immune system will not normally react to cells bearing these genetically determined markers (self-tolerance) Self versus Non-Self Any substance that is recognized as foreign and is capable of triggering an immune response is called an antigen (non self) - Antigens are recognized by lymphocytes which bind to and detect the characteristic shape of an exposed portion (epitope) - Lymphocytes trigger antibody production (adaptive immunity) which specifically bind to epitopes via complementary paratopes Self versus Non-Self Antigenic determinants include: - Surface markers present on foreign bodies in the blood and tissue – including bacterial, fungal, viral and parasitic markers - The self markers of cells from a different organism (this is why transplantation often results in graft rejection) - Even proteins from food may be rejected unless they are first broken down into component parts by the digestive system Antigens on the surface of red blood cells stimulate antibody production in a person with a different blood group. - Different organisms have distinct self markers which prevent transplantation of tissues (unless a very close genetic match) Red blood cells are not nucleated and hence do not possess the same distinctive and unique self markers as all other body cells - This means that red blood cells can be transferred between individuals without automatically causing immune rejection However, red blood cells do possess basic antigenic markers which limit the capacity for transfusion (the ABO blood system) - Red blood cells may possess surface glycoproteins (A and B antigens) either independently (A or B) or in combination (AB) - Alternatively, red blood cells may possess neither surface glycoprotein (denoted as O) As humans produce antibodies against foreign antigens, blood transfusions are not compatible between certain blood groups AB blood groups can receive blood from any other type (as they already possess both antigenic variants on their cells) A blood groups cannot receive B blood or AB blood (as the B isoantigen is foreign and will stimulate antibody production) B blood groups cannot receive A blood or AB blood (as the A isoantigen is foreign and will stimulate antibody production) O blood groups can only receive transfusions from other O blood donor (both antigenic variants are foreign) An additional glycoprotein (Rhesus factor) is either present or absent, resulting in positive and negative blood groups  Recognize the cells and organs of the immune system and their functions The key primary lymphoid organs of the immune system are the thymus and bone marrow, and secondary lymphatic tissues such as spleen, tonsils, lymph vessels, lymph nodes, adenoids, and skin and liver. The bone marrow is extremely important to the immune system because all the body's blood cells (including T and B lymphocytes) originate in the bone marrow. B lymphocytes remain in the marrow to mature, while T lymphocytes travel to the thymus.  Leukocytes (white blood cells) act like independent, single-celled organisms and are the second arm of the innate immune system. The innate leukocytes include the phagocytes ( macrophages, neutrophils, and dendritic cells ), mast cells, eosinophils, basophils, and natural killer cells. These cells identify and eliminate pathogens and are also important mediators in the activation of the adaptive immune system. The cells of the adaptive immune system are special types of leukocytes, called lymphocytes. B cells and T cells are the major types of lymphocytes and are derived from hematopoietic stem cells in the bone marrow.  The lymphatic system is a part of the circulatory system, comprising a network of conduits called lymphatic vessels. The lymphatic system has multiple functions such as the transportation of white blood cells to and from the lymph nodes into the bones.  The defense mechanisms comprise: Innate Immunity Adaptive Immunity  Innate immunity oThis is a mechanism that we are born with. oSkin and mucous membranes act as physical barriers. (secretions-inhospitable environment for pathogens) oThey prevent the entry of pathogens in our body.  Innate immunity oIf a pathogen crosses the physical barriers, it is challenged by phagocytes. oPhagocytes include macrophages, neutrophils etc. oPhagocyted engulf and destroy the microorganisms.  Adaptive immunity oAcquired after birth oAlso known as acquired immunity.  Innate immunity Acquired immunity Doesn’t recognize Recognizes antigens antigens Non-specific Specific Doesn’t improve on Improves on repeated repeat exposure to exposure to the same same pathogen pathogen Acquired Immunity It is provided by some cells and molecules. These cells and molecules recognizes chemicals called antigens. A given immune cell or molecule can recognize only one antigen.  IMMUNOGLOBULINS Immunoglobulins include a diverse group of proteins (Globulins), which have antibody activity. They are synthesized and secreted by B cells in response to invasion of an antigen. Immunoglobulins are also called antibodies. Antibodies are proteins that your immune system makes to fight germs, such as viruses and bacteria. When you're exposed to germs, your body makes unique antibodies that are specifically designed to destroy only those germs. High levels of IgG may mean you have an infection or an inflammatory or autoimmune disease that involves your central nervous system. An autoimmune disorder causes your immune system to attack your own healthy cells by mistake, which can lead to serious health problems Low levels of immunoglobulins mean your immune system isn't working as well as it should. This can be caused by: Medicines that weaken your immune system, such as steroids. Diabetes complications T cells (T Lymphocytes) T cells are a part of the immune system that focuses on specific foreign particles. Rather than generically attack any antigens, T cells circulate until they encounter their specific antigen. As such, T cells play a critical part in immunity to foreign substances. Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response. They can act as “killer cells”, attacking cells which have been infected with a virus or another kind of pathogen, or they can act as “helper cells” by supporting B cells to produce antibodies An increased T cell count may be due to: Cancer of white blood cell called a lymphoblast ( acute lymphoblastic leukemia ) Cancer of white blood cells called lymphocytes ( chronic lymphocytic leukemia ) A viral infection called infectious mononucleosis. T cells receptors T-cell receptors bind to certain antigens (proteins) found on abnormal cells, cancer cells, cells from other organisms, and cells infected with a virus or another microorganism. This interaction causes the T cells to attack these cells and helps the body fight infection, cancer, or other diseases. Also called TCR There are two types of T cell receptor (TCR); alpha beta and gamma delta, both of which are composed of a heterodimer and associated with invariant CD3 complexes on the cell surface. Do an article review on: (Group work) Impact of Immunization Technology and Assay Application on Antibody Performance – A Systematic Comparative Evaluation Give your conclusion on how immunization is related or significant to immunochemistry SEAT WORK