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Copyright 2010. PEER.tamu.edu. Immunity – The War Against Infection Immunity: ability of an organism to resist disease. Immunity: ability of an organism.

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Presentation on theme: "Copyright 2010. PEER.tamu.edu. Immunity – The War Against Infection Immunity: ability of an organism to resist disease. Immunity: ability of an organism."— Presentation transcript:

1 Copyright PEER.tamu.edu

2 Immunity – The War Against Infection Immunity: ability of an organism to resist disease. Immunity: ability of an organism to resist disease. Antigen: any substance that elicits an immune response. Antigen: any substance that elicits an immune response. Antibodies: made in response to specific antigens; can inactivate the antigen that triggered the antibody formation. Antibodies: made in response to specific antigens; can inactivate the antigen that triggered the antibody formation.

3 The Body Fights Back: 2 Ways Surface Barriers Keep Intruders Out Surface Barriers Keep Intruders Out Prevents entry of antigens inside our body Prevents entry of antigens inside our body Skin, Mucosa Skin, Mucosa Two immune mechanisms: Two immune mechanisms: Cell Mediated Immunity: Cell activates itself to defend against the attack Cell Mediated Immunity: Cell activates itself to defend against the attack Humoral Immunity: Cell produces antibodies carried in blood to combat the intrusion Humoral Immunity: Cell produces antibodies carried in blood to combat the intrusion

4 The Invaders The Antigen The Enemy Invader Usually a bacteria or virus

5 The Warriors Three Defense Systems: 1. Macrophage cells 2. Lymphocyte (white blood cell) T cells 3. Lymphocyte (white blood cell) B cells

6 The Macrophage Body's Radar Type of cell normally present in the blood Detects the enemy and engulfs (eats) it This is cell-mediated immunity. The Warriors

7 The T-Helper Cell Communication Link Communication Link Between the body's macrophages and B- cells This is inactivated in HIV infections!

8 Macrophage Presents Antigen to T Cells (white blood cells) Virus

9 The B-Cell (white blood cell) The War Factory Produces antibodies custom tailored for the type of enemy antigen The Warriors

10 B-Cells in Action Virus

11 Antibodies Antigen Busters Designed to seek and destroy the specific enemy antigen Antibodies Need Help Complement Support Troops Assists the antibodies to neutralize the enemy antigen

12 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)

13 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.

14 ELISA TEST-One Way to Test for Antibodies Remove blood cells and use the fluid (serum) to test for presence of antibody. Place target sample on a support. Add serum that has antibody against antigen being tested for. Antibody, if present, binds the antigen. Add a second antibody that was separately developed to react with the antibody/antigen complex in step B and binds it to the complex. Second antibody was also prepared with an enzyme attached to it. This new complex is made visible by reacting it with an enzyme that converts it to a colored compound that you can see.

15 Cell-mediated immunity It is an immune response that does not involve antibodies, but rather the cells act as the killers themselves. It is an immune response that does not involve antibodies, but rather the cells act as the killers themselves. It protects the body by: It protects the body by: Activating antigen-specific T-cells that destroy infected cells. Activating antigen-specific T-cells that destroy infected cells. Activating macrophages that destroy intracellular pathogens. Activating macrophages that destroy intracellular pathogens. Activating NK (Natural Killer) cells that release a protein that kills the target cells Activating NK (Natural Killer) cells that release a protein that kills the target cells

16 Review 1 What is the enemy called that invades the cell? What is the enemy called that invades the cell? What keeps intruders out? What keeps intruders out? What are the two kinds of immunity? What are the two kinds of immunity?

17 Surface Barriers or Mucosal Immunity Skin Skin Cilia Cilia Tears, Saliva, Urine. Tears, Saliva, Urine. Sticky mucus Sticky mucus Stomach: Stomach: Hydrochloric Acid Hydrochloric Acid

18 Analogy Suppose the classroom is a body. Suppose the classroom is a body. All students are cells. All students are cells. Rats are Antigens. Rats are Antigens. Doors and Windows prevent them from entering - Surface Barriers. 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 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. Some of you Brainiacs (B-cells) will call pest control (Antibodies) to capture the rodents – Humoral Immunity.

19 What do these components look like? Source: National Library of MedicineNational Library of Medicine White Blood Cells: Other Blood Components:

20 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

21 The Role of Turn into Macrophages Note the notch in the nucleus. Otherwise, it looks like a lymphocyte. MonocytesEosinophils Attack Internal Parasites Note the red granules in the cytoplasm.

22 Role of Lymphocytes They play a major role in defending the host from both tumors and virally infected cells They play a major role in defending the host from both tumors and virally infected cells There are two main types of lymphocytes: B cells and T cells. There are two main types of lymphocytes: B cells and T cells. The B cells make antibodies that attack bacteria and toxins while the T cells attack body cells themselves when they have been taken over by viruses or have become cancerous. The B cells make antibodies that attack bacteria and toxins while the T cells attack body cells themselves when they have been taken over by viruses or have become cancerous. They are often present at sites of chronic inflammation. They are often present at sites of chronic inflammation.

23 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.

24 The Role of Platelets Blood Clotting They can clump together to form clots. No role in immunity. In this micro-photo of blood cells, platelets are stained purple. A T-Lymphocyte white cell is stained green, and a Monocyte white cell is stained gold. Red blood cells are red.

25 Stop and Review What are the types of white blood cells? What are the types of white blood cells? What is the function of each of the types of white blood cells? What is the function of each of the types of white blood cells? What is the role of platelets? What is the role of platelets?

26 Complete Blood Count (CBC) Whether it is a human, dog, cat, steer, bird or even ferret, when sick, their doctors typically draw a blood sample and perform some tests to help determine a diagnosis. Whether it is a human, dog, cat, steer, bird or even ferret, when sick, their doctors typically draw a blood sample and perform some tests to help determine a diagnosis. The first test generally used is the complete blood count (CBC), which determines the number and types of blood cells present. The first test generally used is the complete blood count (CBC), which determines the number and types of blood cells present. This test can provide information about the status of the patients immune system. This test can provide information about the status of the patients immune system.

27 Complete Blood Count (CBC) Blood is tested for several things: Blood is tested for several things: Red Blood Cells Red Blood Cells White Blood Cells White Blood Cells Total count and percent values for each type of white blood cell Total count and percent values for each type of white blood cell Platelets Platelets Other blood components Other blood components hemoglobin hemoglobin hematocrit hematocrit Click Here for a chart of normal blood values in dogs and cats

28 Leukocytosis Leukocytosis: white blood cell count increased above the normal range. Leukocytosis: white blood cell count increased above the normal range. It is not a disorder or a disease, but a sign of illness. It is not a disorder or a disease, but a sign of illness. It occurs in response to a wide variety of conditions, including It occurs in response to a wide variety of conditions, including viral, bacterial, fungal, or parasitic infection viral, bacterial, fungal, or parasitic infection cancer cancer Hemorrhage (internal bleeding) Hemorrhage (internal bleeding) exposure to certain medications or chemicals including steroids. exposure to certain medications or chemicals including steroids.

29 Leukopenia Leukopenia: a decrease in the number of circulating white blood cells in the blood. 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. As white blood cells get used up during infection, leukopenia can place patients at higher risk for infection. Causes: Causes: Influenza, typhus, malaria, HIV, tuberculosis, dengue, Rickettsial infections, enlargement of the spleen and folate deficiencies. Influenza, typhus, malaria, HIV, tuberculosis, dengue, Rickettsial infections, enlargement of the spleen and folate deficiencies. chemotherapy, radiation therapy, leukemia, myelofibrosis and anemia. chemotherapy, radiation therapy, leukemia, myelofibrosis and anemia. many common medications like minocyclen. many common medications like minocyclen.

30 Immune Disorders in Humans and Animals: HIV (Human Immunodeficiency Virus) HIV infection in humans causes AIDS (Acquired Immunodeficiency Syndrome). HIV infection in humans causes AIDS (Acquired Immunodeficiency Syndrome). AIDS causes the immune system to fail, leading to life- threatening opportunistic infections. 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. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. The four major routes of transmission are The four major routes of transmission are unprotected sexual intercourse, unprotected sexual intercourse, contaminated needles contaminated needles breast milk breast milk transmission from an infected mother to her baby at birth. transmission from an infected mother to her baby at birth.

31 AIDS (Acquired ImmunoDeficiency Syndrome) Virus infects vital cells such as helper T cells and macrophages. 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. When T cell numbers decline below a critical level, cell- mediated immunity is lost, and infections with a variety of opportunistic microbes appear. Illustration of the AIDS virus penetrating a white blood cell and duplicating.

32 Similar to HIV, FIV is a condition in cats that is caused by a virus and causes a reduction in the ability of the immune system of the cat to fight infection and illness. Similar to HIV, FIV is a condition in cats that is caused by a virus and causes a reduction in the ability of the immune system of the cat to fight infection and illness. It is sometimes known as Feline AIDS. It is sometimes known as Feline AIDS. You can't catch AIDs from a cat and a cat can't catch AIDs from an HIV infected person. This is not a zoonotic disease. You can't catch AIDs from a cat and a cat can't catch AIDs from an HIV infected person. This is not a zoonotic disease. Feline Immunodeficiency Virus (FIV) Feline Immunodeficiency Virus (FIV) Click here for more information about FIV See slide note for more resources

33 FIV continued Transmission: Bite wounds from infected cats, especially during cat fights, rarely by milk or during birth. Transmission: Bite wounds from infected cats, especially during cat fights, rarely by milk or during birth. Infected cats may appear normal for years. However, infection eventually leads to a state of immune deficiency. The same agents found in the everyday environment--where they usually do not affect healthy cats--can cause severe illness in cats with weakened immune systems. Infected cats may appear normal for years. However, infection eventually leads to a state of immune deficiency. The same agents found in the everyday environment--where they usually do not affect healthy cats--can cause severe illness in cats with weakened immune systems. There is now also a vaccine to help protect cats from FIV, however it does not provide complete protection. There is now also a vaccine to help protect cats from FIV, however it does not provide complete protection. Cat with Feline Immunodeficiency Virus

34 Caused by a virus similar to HIV and FIV. Caused by a virus similar to HIV and FIV. Transmitted in the saliva and nasal secretions of infected cats. Transmitted in the saliva and nasal secretions of infected cats. Also transmitted by urine, feces and milk. Also transmitted by urine, feces and milk. Unsupervised outdoor cats are most at risk. Unsupervised outdoor cats are most at risk. This infection can lead to cancer in cats, blood disorders, and immunodeficiency which causes cat to be unable to protect itself against infections. This infection can lead to cancer in cats, blood disorders, and immunodeficiency which causes cat to be unable to protect itself against infections. There is a vaccine available for FeLV. There is a vaccine available for FeLV. Feline Leukemia Virus (FeLV) Click here for more information on FeLV

35 A recessive genetic disorder that affects Arabian horses. This condition is fatal, as the animal inevitably succumbs to an opportunistic infection within the first four to six months of life. A recessive genetic disorder that affects Arabian horses. This condition is fatal, as the animal inevitably succumbs to an opportunistic infection within the first four to six months of life. Carriers, who themselves are not affected by the disease, can be detected with a DNA test. Careful breeding practices can avoid the risk of an affected foal being produced. Carriers, who themselves are not affected by the disease, can be detected with a DNA test. Careful breeding practices can avoid the risk of an affected foal being produced. Dogs are also known to have SCID. There are two known forms, an X-linked SCID in Basset Hounds, and a recessive form seen in one line of Jack Russell Terriers that is similar to SCID in Arabian horses. Dogs are also known to have SCID. There are two known forms, an X-linked SCID in Basset Hounds, and a recessive form seen in one line of Jack Russell Terriers that is similar to SCID in Arabian horses. Severe Combined Immunodeficiency Disease in Animals (SCID)

36 Review 3 What is a CBC? What is a CBC? What is Leukopenia and what are its causes? What is Leukopenia and what are its causes? What is Leukocytosis and what could it be an indicator of? What is Leukocytosis and what could it be an indicator of? Name four immune disorders and tell what causes them and what species they affect Name four immune disorders and tell what causes them and what species they affect


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