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Questions and Answers
What is the primary function of C-reactive protein in the immune response?
What is the primary function of C-reactive protein in the immune response?
Which of the following signs is NOT typically associated with inflammation?
Which of the following signs is NOT typically associated with inflammation?
What stimulates the proliferation of white blood cells systemically during inflammation?
What stimulates the proliferation of white blood cells systemically during inflammation?
Which type of T lymphocyte is primarily responsible for activating macrophages?
Which type of T lymphocyte is primarily responsible for activating macrophages?
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What is the role of the Fab region in an antibody molecule?
What is the role of the Fab region in an antibody molecule?
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What distinguishes CD8+ T lymphocytes from CD4+ T lymphocytes?
What distinguishes CD8+ T lymphocytes from CD4+ T lymphocytes?
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Which class of antibodies plays a critical role in defense against helminths?
Which class of antibodies plays a critical role in defense against helminths?
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What happens during extravasation in response to inflammation?
What happens during extravasation in response to inflammation?
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What is one of the main functions of macrophages?
What is one of the main functions of macrophages?
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Which cells are primarily involved in the defense against parasitic infections?
Which cells are primarily involved in the defense against parasitic infections?
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Which pathway of the complement system is initiated by the binding of mannose-binding lectin?
Which pathway of the complement system is initiated by the binding of mannose-binding lectin?
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What is the primary role of dendritic cells in the immune response?
What is the primary role of dendritic cells in the immune response?
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What triggers inflammation in the complement system?
What triggers inflammation in the complement system?
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What is a significant feature of Natural Killer (NK) cells?
What is a significant feature of Natural Killer (NK) cells?
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Which of the following cells is classified as part of the second line of defense?
Which of the following cells is classified as part of the second line of defense?
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Acute phase proteins are primarily produced by which organ?
Acute phase proteins are primarily produced by which organ?
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What distinguishes adaptive immunity from innate immunity?
What distinguishes adaptive immunity from innate immunity?
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Which of the following is NOT a feature of innate immunity?
Which of the following is NOT a feature of innate immunity?
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What role do lysozymes play in innate immunity?
What role do lysozymes play in innate immunity?
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Which component is considered a first line of defense in the respiratory tract?
Which component is considered a first line of defense in the respiratory tract?
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Which of the following statements about the digestive tract's role in innate immunity is correct?
Which of the following statements about the digestive tract's role in innate immunity is correct?
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What characterizes the second line of defense in innate immunity?
What characterizes the second line of defense in innate immunity?
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How does the genitourinary tract contribute to the immune system?
How does the genitourinary tract contribute to the immune system?
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Which of the following characters is associated with adaptive immunity?
Which of the following characters is associated with adaptive immunity?
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What distinguishes an immunogen from an antigen?
What distinguishes an immunogen from an antigen?
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What is a hapten?
What is a hapten?
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Which type of antibodies recognize multiple epitopes on the same antigen?
Which type of antibodies recognize multiple epitopes on the same antigen?
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During the production of monoclonal antibodies, what happens to the fused cells?
During the production of monoclonal antibodies, what happens to the fused cells?
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What role does the selection culture medium play in monoclonal antibody production?
What role does the selection culture medium play in monoclonal antibody production?
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What is the significance of single hybridoma cells in the production of monoclonal antibodies?
What is the significance of single hybridoma cells in the production of monoclonal antibodies?
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What is the role of polyethylene glycol (PEG) in the production of hybridomas?
What is the role of polyethylene glycol (PEG) in the production of hybridomas?
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How is the supernatant of hybridoma clones utilized in the antibody production process?
How is the supernatant of hybridoma clones utilized in the antibody production process?
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Study Notes
Introduction to Immunity
- Immunity is the body's resistance to diseases.
- Two main types of immunity: innate and adaptive.
- Innate immunity is non-specific, present at birth, always ready, immediate, and composed of the first and second lines of defense.
- Adaptive immunity is specific, acquired later in life, activated only after encountering microbes, delayed, and includes humoral and cellular responses.
The First Line of Defense: External Defenses
- This line prevents microbes from entering the body through physical, chemical, and biological barriers.
- Skin: acts as a physical barrier, maintains a pH of 5.6, produces psoriasin with antibacterial effects.
- Tears and saliva: contain lysozyme, an enzyme that attacks microbial cell walls.
- Respiratory tract: mucous traps microbes, cilia expel mucus, coughing and sneezing remove pathogens.
- Genitourinary tract: urine flow helps remove pathogens.
- Digestive tract: stomach acidity (pH 1) kills microbes, gut microbiota prevents pathogen colonization.
The Second Line of Defense: Internal Defenses
- Activated when microbes bypass the first line of defense.
- Composed of cells and proteins.
- Cells include: macrophages, dendritic cells, neutrophils, eosinophils, basophils, NK cells, and mast cells.
- Proteins include: complement proteins, acute phase proteins, and cytokines.
Macrophages
- Ingest and destroy microbes.
- Produce inflammatory cytokines.
- Clear dead cells and initiate tissue repair.
- Act as antigen-presenting cells (APCs).
Dendritic Cells
- Produce inflammatory cytokines.
- The most efficient antigen-presenting cells (APCs).
Neutrophils
- The most abundant white blood cells in the blood.
- First responders to infection.
- Phagocytose and destroy microbes.
- Generate neutrophil extracellular traps (NETs) to kill bacteria.
- Important for defending against bacterial infections.
Eosinophils
- Defend against parasitic infections.
- Play a role in allergic reactions.
Basophils
- Circulate in the blood.
- Very rare.
- Involved in inflammation and allergy.
Mast Cells
- Reside in tissues.
- Resemble basophils.
- Involved in inflammation and allergy.
Natural Killer Cells (NK Cells)
- Lymphocyte-like cells.
- Kill virus-infected cells and tumor cells.
- Activate macrophages to kill phagocytosed microbes.
Complement System
- Series of inactive proteins in the serum.
- Activated by infection.
- Three pathways: classical, alternative, and lectin.
- Activation results in inflammation, opsonization/phagocytosis, and lysis of microbes.
Acute Phase Proteins
- Produced by the liver.
- Increase rapidly after infection.
- Examples include: C-reactive protein, complement C3, mannose-binding lectin, and fibrinogen.
Inflammation
- A tissue response to infection or damage.
- Brings immune mediators, including cells and proteins, to the site of infection.
- Characterized by vasodilation, increased capillary permeability, extravasation, and migration of white blood cells.
- Systemic responses include fever and increased white blood cell production.
- Signs include heat, redness, swelling, and pain.
Adaptive Immunity
- Mediated by T lymphocytes and antibodies.
- Cell-mediated immunity: mediated by T lymphocytes (CD4+ and CD8+).
- Humoral immunity: mediated by antibodies produced by B lymphocytes and plasma cells.
Cell-mediated Immunity
- Mediated by T lymphocytes.
-
CD4+ T lymphocytes (helper T cells):
- Recognize peptide antigens presented by MHC class II molecules.
- Have subsets with distinct functions:
- Th1: activate macrophages to kill ingested microbes.
- Th2: important in defending against parasites.
- Th17: induce inflammatory reactions to destroy extracellular bacteria.
- Tfh: help in antibody production.
-
CD8+ T lymphocytes (cytotoxic T lymphocytes, CTLs):
- Recognize peptide antigens presented by MHC class I molecules.
- Kill virus-infected and tumor cells.
Humoral Immunity: Antibodies
- Form the immunoglobulin family of proteins.
- Produced by B lymphocytes and plasma cells.
- Exist in two forms:
- Membrane-bound: act as B cell receptors.
- Secreted: effector molecules of humoral immunity.
- Five classes/isotypes: IgM, IgG, IgA, IgE, and IgD.
- Each isotype performs distinct effector functions.
Antibody Structure
- Y-shaped molecule.
- Composed of two identical light chains and two identical heavy chains.
- Each monomeric antibody has two identical antigen-binding sites.
- Fab region: arms of the Y shape, contains the antigen-binding site.
- Fc region: stem of the Y shape, responsible for effector functions (e.g., complement activation).
Antigen, Immunogen, Hapten, and Epitope
- Antigen: any substance that binds specifically to an antibody or T cell receptor.
- Immunogen: any substance that can induce an immune response. All immunogens are antigens, but not all antigens are immunogens.
- Hapten: a small molecule that is an antigen but not immunogenic unless attached to a carrier protein.
- Epitope: the specific part of an antigen recognized by an antibody.
Antibody Production for Lab Use
- Most immunology/serology tests use antibodies as reagents.
- Two types of antibodies used in the lab: polyclonal and monoclonal.
- Polyclonal antibodies: a collection of antibodies from different B cell clones recognizing multiple epitopes on the same antigen.
- Monoclonal antibodies: produced by a single B cell clone, recognize a single epitope on the antigen.
Production of Polyclonal Antibodies
- An animal (e.g., rabbit) is immunized with an antigen.
- The animal's serum containing the polyclonal antibodies is collected.
Production of Monoclonal Antibodies
- A mouse is immunized with an antigen.
- Spleen cells are harvested (contain B cells producing antibodies).
- Spleen cells are fused with myeloma cells (immortal cells) to produce hybridomas (cells capable of producing antibodies and growing indefinitely).
- Hybridomas are selected and cultured, and their supernatants are screened for the desired antibody.
- Clones producing the desired antibody are maintained and used to produce monoclonal antibodies.
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Description
Test your knowledge on the fundamentals of immunity, including the differences between innate and adaptive immunity. Explore the various lines of defense and their roles in protecting the body against pathogens. This quiz will challenge your understanding of the immune system's mechanisms and barriers.
