T Cell Effector Mechanisms and MHC Class 2
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T Cell Effector Mechanisms and MHC Class 2

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Questions and Answers

What is the primary function of T cells in the immune response?

  • To directly kill pathogens
  • To orchestrate cell mediated immunity and regulate B cell response (correct)
  • To produce antibodies
  • To enhance innate immunity

    • How do T cell receptors recognize antigens?

  • Through soluble antibody complexes
  • In native form without any modifications
  • By binding to antigens presented by MHC molecules (correct)
  • By binding directly to the antigen

    • What distinguishes MHC class 1 from MHC class 2?

  • MHC class 1 has one transmembrane domain (correct)
  • MHC class 2 presents antigens to cytotoxic T cells
  • MHC class 1 has two transmembrane domains
  • MHC class 2 is present on all nucleated cells

    • Which statement is true about how B cell receptors differ from T cell receptors?

    <p>B cell receptors can directly recognize and bind to the antigen</p> Signup and view all the answers

    Which type of antigen processing occurs within a virus-infected cell?

    <p>Intracellular degradation</p> Signup and view all the answers

    Why is MHC important for T cell activation?

    <p>It presents processed antigens to T cell receptors</p> Signup and view all the answers

    What happens to T cells after they are specifically activated?

    <p>They help regulate B cell responses and enhance immune reactions</p> Signup and view all the answers

    What is a key difference between adaptive immunity and innate immunity regarding T cells?

    <p>T cells are specifically activated against pathogens in adaptive immunity</p> Signup and view all the answers

    What is the role of antibodies when dealing with smaller parasites?

    <p>To bind to the parasite and facilitate its elimination</p> Signup and view all the answers

    How does the immune system respond to larger, antibody-coated parasites?

    <p>By eosinophils making holes in the parasite</p> Signup and view all the answers

    In cases of immune system deficiency, what is a common consequence observed?

    <p>Increased susceptibility to infectious agents</p> Signup and view all the answers

    What happens when there is a defect in the immune system's ability to recognize its own proteins?

    <p>Autoimmunity can develop</p> Signup and view all the answers

    What is the expected outcome when the immune system is functioning properly against tumors?

    <p>Tumors are cleared by the immune cells</p> Signup and view all the answers

    Which scenario is indicative of a failure in immune system tolerance?

    <p>Organ transplant failure due to rejection</p> Signup and view all the answers

    What is considered the best method to enhance the immune response?

    <p>Vaccination</p> Signup and view all the answers

    What type of immune response occurs when there is a defect triggering allergy?

    <p>Loss of allergic sensitization</p> Signup and view all the answers

    What role do T helper cells play in the immune response to Mycobacterium?

    <p>They activate macrophages through cytokine release.</p> Signup and view all the answers

    What mechanism allows T helper cells to recognize Mycobacterium-infected macrophages?

    <p>Recognition of MHC class II presenting foreign protein.</p> Signup and view all the answers

    What cytokine do T helper cells release to communicate with macrophages?

    <p>Interferon gamma (IFN-γ)</p> Signup and view all the answers

    Which process is necessary for the effective killing of intracellular bacteria by macrophages?

    <p>Fusion of lysosomes with phagosomes.</p> Signup and view all the answers

    What is the primary feature of the TH1 immune response?

    <p>Stimulation of macrophages to destroy pathogens.</p> Signup and view all the answers

    How does the activation of B cells occur in relation to T helper cells?

    <p>B cells need a second signal from T helper cells.</p> Signup and view all the answers

    What type of helper T cells specifically assist in B cell activation?

    <p>T follicular helper cells</p> Signup and view all the answers

    Which of the following statements about T cell receptors is true?

    <p>They require antigen processing for activation.</p> Signup and view all the answers

    What is the primary benefit of vaccination according to the content?

    <p>It protects against the occurrence of diseases.</p> Signup and view all the answers

    Which of the following diseases has not had an effective vaccine developed?

    <p>HIV</p> Signup and view all the answers

    How did the incidence of diphtheria change after the vaccine was introduced?

    <p>It dramatically decreased.</p> Signup and view all the answers

    What type of vaccine is primarily used for polio in India?

    <p>Oral vaccine</p> Signup and view all the answers

    Why is vaccination not always effective according to the content?

    <p>Some individuals' immune systems may not respond properly.</p> Signup and view all the answers

    In what time frame did the incidence of polio start to significantly decrease after vaccination efforts began?

    <p>Post-1990</p> Signup and view all the answers

    What was the trend in measles cases after effective vaccination was implemented?

    <p>They have shown a gradual decline to almost non-existence.</p> Signup and view all the answers

    How does proper vaccination timing affect disease occurrence?

    <p>It prevents the disease from happening.</p> Signup and view all the answers

    What is subacute sclerosing panencephalitis (SSP)?

    <p>A brain disease that can occur after a measles infection</p> Signup and view all the answers

    In healthy individuals, what role does the immune system play regarding diseases?

    <p>It often eliminates diseases before they develop</p> Signup and view all the answers

    Why is studying immunology considered important?

    <p>To develop more effective vaccines and treatments</p> Signup and view all the answers

    What is a significant concern regarding antibiotics mentioned in the content?

    <p>The emergence of antibiotic-resistant strains of bacteria</p> Signup and view all the answers

    What happens to the likelihood of diseases in AIDS patients according to the content?

    <p>They are more susceptible to various infections</p> Signup and view all the answers

    What is the potential outcome of further understanding the immune system?

    <p>Enhanced methods for activating the immune system</p> Signup and view all the answers

    How does the content describe the overall functioning of the immune system?

    <p>It generally functions well but requires further study</p> Signup and view all the answers

    What is the main focus of ongoing research in immunology as mentioned?

    <p>To control and enhance the immune response</p> Signup and view all the answers

    Study Notes

    T Cell Effector Mechanisms

    • T cells are responsible for cell-mediated immunity, which helps regulate B cell responses to most antigens.
    • T cells must be specifically activated against a particular pathogen or antigen, unlike innate immunity.
    • T cell receptors cannot recognize antigens in their native state, they require help from MHC (Major Histocompatibility Complex) molecules.
    • MHC Class 1 and MHC Class 2 are the two types of MHC molecules.
    • The differences between MHC Class 1 and MHC Class 2 include the number of transmembrane domains anchoring them to the cell membrane. MHC Class 1 has one transmembrane domain, while MHC Class 2 has two.

    MHC Class 2 and T Helper Cells

    • MHC Class 2 molecules present processed antigens on the surface of macrophages. This process is crucial for the recognition of intracellular pathogens like Mycobacterium.
    • When a macrophage presents a foreign antigen on MHC Class 2, T helper cells recognize the antigen, activating them.
    • Activated T helper cells release cytokines like interferon gamma, which signals macrophages to fuse with lysosomes to kill intracellular bacteria. This is called the TH1 response.

    The Importance of T Helper Cells in B Cell Activation

    • T helper cells are also essential for the activation of B cells.
    • B cells can directly interact with antigens, but this interaction alone is not sufficient to activate them.
    • B cells need an additional signal from T follicular helper cells to become fully activated.

    Different Immune Responses Based on Pathogen Size

    • Antibodies play a role in fighting smaller parasites, binding to them directly.
    • The TH1 response is triggered by intracellular pathogens.
    • Eosinophils are crucial in killing larger parasites coated with antibodies.

    Immune Deficiencies and Their Consequences

    • Immune deficiencies can result from inherited or acquired defects in the immune system.
    • Recurrent infections occur when the immune system is deficient, as it cannot properly fight off pathogens.
    • Allergy is a normal response to innocuous substances, but deficiencies can lead to an absence of allergic reactions.
    • Organ rejection after transplantation is a normal response of the immune system, however, deficiencies can lead to acceptance of grafted organs.
    • Autoimmunity occurs when the immune system fails to recognize its own proteins or tissues, leading to a reaction against the body's own cells.

    Vaccination as the Best Protection

    • Vaccination is the most effective way to induce immunity against specific diseases.
    • Vaccines help train the immune system, preventing the development of diseases altogether.
    • Unfortunately, not all diseases have effective vaccines yet. For example, there are currently no effective vaccines against HIV or malaria.

    Examples of Highly Effective Vaccines

    • Diphtheria vaccine has dramatically reduced cases of the disease since its introduction in 1945.
    • Polio vaccination has drastically decreased polio cases, particularly in India.
    • Measles vaccine has significantly lowered measles cases and the rare complication known as subacute sclerosing panencephalitis (SSP).

    The Importance of Studying and Researching the Immune System

    • The human immune system is remarkably complex and still not fully understood.
    • Ongoing research is crucial to better understand and manipulate the immune system.
    • Further research opens up possibilities for developing new, more effective vaccines and combating infectious diseases.
    • Future research is also essential for understanding antibiotic resistance and finding new ways to fight bacterial infections.

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    Lecture 5: Basic Concepts in Immunology (Contd.) PDF

    Description

    Explore the mechanisms of T cell effector functions and the role of MHC Class 2 molecules in the immune response. This quiz covers topics like cell-mediated immunity, the differences between MHC Class 1 and Class 2, and the activation of T helper cells. Test your knowledge on how T cells interact with antigens and regulate immune responses.

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