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Questions and Answers
What is the primary function of CD4+ effector T cells in the Th1 subset?
What is the primary function of CD4+ effector T cells in the Th1 subset?
Which type of T cells are primarily responsible for killing infected cells harboring cytoplasmic microbes?
Which type of T cells are primarily responsible for killing infected cells harboring cytoplasmic microbes?
What role do Th17 cells play in the immune response?
What role do Th17 cells play in the immune response?
Which statement accurately describes the process by which B lymphocytes respond to protein antigens?
Which statement accurately describes the process by which B lymphocytes respond to protein antigens?
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What key function do dendritic cells perform in initiating T cell activation?
What key function do dendritic cells perform in initiating T cell activation?
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What role does IgG play in relation to macrophages?
What role does IgG play in relation to macrophages?
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Which proteins are part of the B-cell antigen receptor complex?
Which proteins are part of the B-cell antigen receptor complex?
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What is not a function of dendritic cells (DCs)?
What is not a function of dendritic cells (DCs)?
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What type of receptors do B cells use to recognize complement products?
What type of receptors do B cells use to recognize complement products?
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Where do the principal primary lymphoid organs exist?
Where do the principal primary lymphoid organs exist?
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Which of the following statements about secondary lymphoid organs is true?
Which of the following statements about secondary lymphoid organs is true?
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What common virus uses CR2 as a receptor to infect B cells?
What common virus uses CR2 as a receptor to infect B cells?
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Which immune cell plays a pivotal role in the initiation of T-cell responses?
Which immune cell plays a pivotal role in the initiation of T-cell responses?
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What is the main function of Igα and Igβ in the B-cell antigen receptor complex?
What is the main function of Igα and Igβ in the B-cell antigen receptor complex?
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What is a primary role of natural killer cells in innate immunity?
What is a primary role of natural killer cells in innate immunity?
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Which type of hypersensitivity reaction involves antibodies targeting antigens on cell surfaces?
Which type of hypersensitivity reaction involves antibodies targeting antigens on cell surfaces?
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What does immunologic tolerance primarily refer to?
What does immunologic tolerance primarily refer to?
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Which mechanism is involved in CD4+ T cell-mediated inflammation?
Which mechanism is involved in CD4+ T cell-mediated inflammation?
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What distinguishes systemic lupus erythematosus from other autoimmune diseases?
What distinguishes systemic lupus erythematosus from other autoimmune diseases?
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In the context of graft rejection, what is the primary role of the Major Histocompatibility Complex (MHC)?
In the context of graft rejection, what is the primary role of the Major Histocompatibility Complex (MHC)?
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Which cytokines are primarily involved in the activation of Th2 cells during immediate hypersensitivity?
Which cytokines are primarily involved in the activation of Th2 cells during immediate hypersensitivity?
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What role do costimulatory molecules such as CD80 and CD86 play in T lymphocyte activation?
What role do costimulatory molecules such as CD80 and CD86 play in T lymphocyte activation?
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Which cytokine is NOT mentioned as an example of a costimulatory signal during the innate immune response?
Which cytokine is NOT mentioned as an example of a costimulatory signal during the innate immune response?
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What therapeutic role do cytokine antagonists serve in patients with rheumatoid arthritis?
What therapeutic role do cytokine antagonists serve in patients with rheumatoid arthritis?
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In the context of T lymphocyte activation, what does 'signal 1' refer to?
In the context of T lymphocyte activation, what does 'signal 1' refer to?
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Why is 'signal 2' important for the adaptive immune response?
Why is 'signal 2' important for the adaptive immune response?
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What is the primary function of cytokines produced during innate immune responses?
What is the primary function of cytokines produced during innate immune responses?
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Which of the following best describes the relationship between innate and adaptive immune responses?
Which of the following best describes the relationship between innate and adaptive immune responses?
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What is a consequence of the inhibition of cytokine production?
What is a consequence of the inhibition of cytokine production?
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In immune responses to tumors, what role might necrotic cells play?
In immune responses to tumors, what role might necrotic cells play?
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What is the primary function of effector CD4+ T cells in relation to macrophages?
What is the primary function of effector CD4+ T cells in relation to macrophages?
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How do Th2 cells contribute to the immune response against helminthic parasites?
How do Th2 cells contribute to the immune response against helminthic parasites?
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What is the role of dendritic cells (DCs) in the immune system?
What is the role of dendritic cells (DCs) in the immune system?
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What ultimately results from classical macrophage activation?
What ultimately results from classical macrophage activation?
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Which cytokine is primarily responsible for activating eosinophils?
Which cytokine is primarily responsible for activating eosinophils?
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Why are secondary lymphoid organs vital in the immune response?
Why are secondary lymphoid organs vital in the immune response?
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What type of molecule do B lymphocytes use to recognize antigens?
What type of molecule do B lymphocytes use to recognize antigens?
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What mechanism do eosinophils employ to eliminate helminths?
What mechanism do eosinophils employ to eliminate helminths?
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What outcome does the combination of CD40- and IFN-γ-mediated activation achieve?
What outcome does the combination of CD40- and IFN-γ-mediated activation achieve?
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Which of the following describes Th1 cells' role in the immune response?
Which of the following describes Th1 cells' role in the immune response?
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Study Notes
Immune System Diseases
- The immune system is vital for survival, protecting against infections and cancers. Immune deficiencies make individuals vulnerable to infections and increase cancer risk. Immune responses can cause tissue damage and disease (allergies and autoimmunity).
- Innate immunity provides rapid, immediate defense, recognizing microbial products. Key components include epithelial barriers (e.g., skin), phagocytic cells (neutrophils, macrophages), dendritic cells, natural killer cells, and complement proteins.
- Adaptive immunity develops more slowly, responding specifically to microbes and foreign substances, displaying memory. This involves lymphocytes (B and T cells) with highly diverse receptors (antibodies and T cell receptors) to recognize a vast array of antigens.
- Class I MHC molecules are displayed on all nucleated cells and platelets, recognizing peptides from cytoplasmic proteins (normal or pathogen-associated). CD8+ cells are responsible for recognizing these peptide-MHC complexes.
- Class II MHC molecules display peptides from extracellular antigens, recognized by CD4+ T cells, which play a crucial role as helper cells.
- Cytokines are messenger molecules crucial for activating various immune cells and mediating essential immune functions in both innate and adaptive immunity. Cytokines can activate cells, promote proliferation, and differentiation and activate various other functions.
- Cellular receptors for microbes, damaged cells, and foreign substances are crucial for innate immunity.
- Natural killer (NK) cells have activating and inhibitory receptors, recognizing healthy or stressed cells (like virus-infected or cancer cells) to destroy them. This is regulated through the interaction between these receptors and the recognized cells.
- Dendritic cells (DCs) are specialized cells residing in tissues and lymphoid organs that capture, process, and present antigens to T cells. They're responsible for initiating adaptive immune responses.
- Lymphocyte diversity enables the recognition of a vast range of antigens. Lymphocytes are crucial for adaptive immunity, and their high diversity helps in detecting a broad array of antigens and mounting an effective response.
- Lymphocyte recirculation maximizes the chances of antigen-specific lymphocytes encountering and responding to antigens in secondary lymphoid tissue through the lymphatic system, where antigen concentration is higher.
- T lymphocytes exist in different sub-types. Helper T cells assist B cells in antibody production and activate other leukocytes, cytotoxic T cells (CTLs) kill infected cells, and regulatory T cells prevent reactions against self-antigens.
- B lymphocytes produce antibodies (the mediators of humoral immunity) which neutralise threats, opsonise pathogens for phagocytosis, and activate the complement system.
Hypersensitivity
- Hypersensitivity reactions are excessive or harmful reactions to antigens (exogenous or endogenous).
- Type I hypersensitivity (immediate): rapid reaction involving IgE antibodies, mast cells, and inflammatory mediators, causing symptoms like allergies and anaphylaxis.
- Type II hypersensitivity (antibody-mediated): antibodies directly attack cells or tissues, leading to phagocytosis or lysis (e.g., autoimmune hemolytic anemia).
- Type III hypersensitivity (immune-complex-mediated): antigen-antibody complexes deposit in tissues and activate complement, triggering inflammation.
- Type IV hypersensitivity (cell-mediated): T cells cause tissue damage, typically by activating macrophages or directly killing cells (e.g., contact dermatitis).
Autoimmune Diseases
- Autoimmune diseases result from immune reactions against self-antigens.
- Systemic lupus erythematosus (SLE): a systemic autoimmune disease involving multiple organs, characterized by a broad range of autoantibodies and immune complexes (e.g., anti-dsDNA antibodies).
- Other notable systemic conditions include Rheumatoid arthritis, systemic sclerosis (scleroderma), and Sjögren Syndrome.
Immunodeficiency Diseases
- Immunodeficiency diseases result from defects in the innate and/or adaptive immune systems.
- Primary immunodeficiencies: inherited genetic defects in immune components, causing increased susceptibility to infections.
- Secondary immunodeficiencies: acquired immunodeficiencies resulting from conditions that impair the immune system (e.g., HIV infection).
- Severe combined immunodeficiency (SCID): a severe deficiency affecting both humoral and cellular immunity, leading to increased infections.
- Other conditions that may result in immunodeficiency include X-linked agammaglobulinemia, IgA deficiency, and digeorge syndrome.
Transplant Rejection
- Transplant rejection is immune-mediated responses against transplanted tissues. Rejection can result from pre-formed antibodies, and T cell mediated responses.
- Hyperacute rejection: caused by pre-formed antibodies against the graft.
- Acute rejection: primarily cell-mediated responses.
- Chronic rejection: a slow, progressive process, often involving vascular damage and fibrosis.
Acquired Immunodeficiency Syndrome (AIDS)
- AIDS is caused by HIV, leading to profound immune deficiency and severe conditions.
- A critical step in the progression of the disease involves loss of CD4+ T cells. This impacts several key components of the adaptive immune response (cell mediated and humoral). The loss of these critical immune cells leads to widespread infections and cancers.
Amyloidosis
- A group of diseases characterized by extracellular deposits of misfolded proteins forming fibrils. Amyloid accumulation damages tissues and compromises organ functions.
- Amyloid forms include AL (immunoglobulin light chains), AA (reactive systemic), ATTR (transthyretin), and Aβ (in Alzheimer's disease).
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Description
Explore the crucial role of the immune system in protecting against infections and cancers. This quiz covers the differences between innate and adaptive immunity, key components involved, and the significance of Class I MHC molecules. Test your knowledge on immune deficiencies, allergies, and autoimmunity.
