Transcript immunity
Copyright 2010. PEER.tamu.edu Immunity – The War Against Infection Immunity: ability of an organism to resist disease. Antigen: any substance that elicits an immune response. Antibodies: made in response to specific antigens; can inactivate the antigen that triggered the antibody formation. The Body Fights Back: 2 Ways Surface Barriers Keep Intruders Out • Prevents entry of antigens inside our body • Skin, Mucosa Two immune mechanisms: • Cell Mediated Immunity: Cell activates itself to defend against the attack • Humoral Immunity: Cell produces antibodies carried in blood to combat the intrusion The Invaders The Antigen The Enemy Invader • Usually a bacteria or virus The Warriors Three Defense Systems: 1. Macrophage cells 2. T cells 3. B cells The Warriors The Macrophage Body's Radar Type of cell normally present in the blood Detects the enemy and engulfs (eats) it The Warriors The T-Helper Cell Communication Link Communication Link Between the body's macrophages and Bcells Inactivated in HIV infections Macrophage Presents Antigen to T Cells Virus Virus Virus The Warriors The B-Cell The War Factory Produces antibodies custom tailored for the type of enemy antigen B-Cells in Action Virus Virus Virus Virus Antibodies Need Help Antibodies Antigen Busters Designed to seek and destroy the specific enemy antigen Complement Support Troops Assists the antibodies to neutralize the enemy antigen Antibody Protein & Humoral Immunity Since antibodies circulate through the body fluids(humours), the protection afforded by B cells is called humoral immunity. Structure of antibodies (Y-shaped proteins) So what does an antibody do? 1. Binds to molecules (antigens) on the surface of invading organism. 2. Inactivates or renders the microorganism susceptible to destruction by the immune system. Review 1 What is the enemy called that invades the cell? What keeps intruders out? What are the two kinds of immunity? Surface Barriers or Mucosal Immunity Skin Cilia Tears, Saliva, Urine. Sticky mucus Stomach: Hydrochloric Acid Analogy Suppose the classroom is a body. All students are cells. Rats are Antigens. Doors and Windows prevent them from entering - Surface Barriers. Some of you Tough ones (T-cells) will capture the rodents - Cell-mediated Immunity. Some of you Brainiacs (B-cells) will call pest control (Antibodies) to capture the rodents – Humoral Immunity. The Cells in Blood Source: National Library of Medicine *Lymphocyte not shown. Looks like a monocyte, except nucleus mostly fills the cell and does not have a notch in it. The Role of Neutrophils When a wound occurs, neutrophils migrate out of blood to rush to the wound and phagocytize (“eat”) the bacteria. This is what pus is made of. “old” neutrophil surrounded by red blood cells The Role of Monocytes Eosinophils Turn into Macrophages Attack Internal Parasites Note the notch in the nucleus. Otherwise, it looks like a lymphocyte. Note the red granules in the cytoplasm. The Role of Macrophages Engulf and then digest cellular debris and microbes in the body tissues. Note the irregular cell membrane. These are monocytes in the bloodstream and once they migrate into the tissues they become macrophages. The Role of Platelets Blood Clotting They can clump together to form clots. No role in immunity. Leukocytosis Leukocytosis: white blood cell count increased above the normal range. It is not a disorder or a disease, but a sign of illness. It occurs in response to a wide variety of conditions, including viral, bacterial, fungal, or parasitic infection cancer Hemorrhage (internal bleeding) exposure to certain medications or chemicals including steroids. Leukopenia Leukopenia: a decrease in the number of circulating white blood cells in the blood. As white blood cells get “used up” during infection, leukopenia can place patients at higher risk for infection. Causes: Influenza, typhus, malaria, HIV, tuberculosis, dengue, Rickettsial infections, enlargement of the spleen and folate deficiencies. chemotherapy, radiation therapy, leukemia , myelofibrosis and anemia. many common medications like minocyclen. HIV (Human Immunodeficiency Virus) HIV infection causes AIDS (Acquired ImmunoDeficiency Syndrome). AIDS causes the immune system to fail, leading to life- threatening opportunistic infections. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. The four major routes of transmission are unprotected sexual intercourse, contaminated needles breast milk transmission from an infected mother to her baby at birth. AIDS (Acquired ImmunoDeficiency Syndrome) Virus infects vital cells such as helper T cells and macrophages. When T cell numbers decline below a critical level, cell-mediated immunity is lost, and infections with a variety of opportunistic microbes appear. Cell-mediated immunity It is an immune response that does not involve antibodies, but rather the cells act as the killers themselves. It protects the body by: Activating antigen-specific T-cells that destroy infected cells. Activating macrophages that destroy intracellular pathogens. Activating NK (Natural Killer) cells that release a protein that kills the target cells Review 3 What is Leukopenia and what does it cause? What immune response does not involve antibodies? Immune System Research How do they test for antibodies? ELISA TEST Remove blood cells and use the fluid (serum) to test for presence of antibody. A. Place target sample on a support B. Add serum that has antibody against antigen being tested for. Antibody, if present, binds the antigen. C. Add a second antibody (that was separately developed to react with the antibody/antigen complex in step B) binds it to the complex. Second antibody was also prepared with an enzyme attached to it. D. This new complex is made visible by reacting it with an enzyme that converts it to a colored compound that you can see.