Podcast
Questions and Answers
Which of the following is NOT a characteristic of the innate immune response?
Which of the following is NOT a characteristic of the innate immune response?
- Non-specific
- Fast
- Generic
- Specific (correct)
Which cells are primarily involved in phagocytosis within the innate immune system?
Which cells are primarily involved in phagocytosis within the innate immune system?
- Lymphocytes
- B cells
- Neutrophils (correct)
- T cells
Which of the following immune cells is responsible for immunological surveillance?
Which of the following immune cells is responsible for immunological surveillance?
- Dendritic Cells
- Natural Killer Cells (correct)
- B cells
- T cells
What are the classical signs of inflammation?
What are the classical signs of inflammation?
Which natural antimicrobial substance is NOT part of the innate immune system?
Which natural antimicrobial substance is NOT part of the innate immune system?
What type of immunity is dependent on the recognition of specific antigens?
What type of immunity is dependent on the recognition of specific antigens?
Which of the following cells is NOT classified as an innate immune cell?
Which of the following cells is NOT classified as an innate immune cell?
Which of the following physical barriers provides defense at body surfaces?
Which of the following physical barriers provides defense at body surfaces?
What is the primary function of memory B cells?
What is the primary function of memory B cells?
Which characteristic is true for memory B cells?
Which characteristic is true for memory B cells?
What is the correct statement about plasma cells?
What is the correct statement about plasma cells?
Which of the following is true about T-cells?
Which of the following is true about T-cells?
Which statement accurately describes the role of antibodies?
Which statement accurately describes the role of antibodies?
What is the presence of CD19 on B-cells indicative of?
What is the presence of CD19 on B-cells indicative of?
What is the primary role of B lymphocytes in the immune system?
What is the primary role of B lymphocytes in the immune system?
Which type of T cells primarily recognize MHC-II molecules?
Which type of T cells primarily recognize MHC-II molecules?
What process happens at the cortex-medulla border of the thymus?
What process happens at the cortex-medulla border of the thymus?
What percentage of thymocytes typically die by apoptosis before reaching maturity?
What percentage of thymocytes typically die by apoptosis before reaching maturity?
Which characteristic do CD8+ T cytotoxic cells express?
Which characteristic do CD8+ T cytotoxic cells express?
How do CD8+ T cytotoxic cells eliminate infected cells?
How do CD8+ T cytotoxic cells eliminate infected cells?
What is one of the key functions of interferon-gamma (IFN-γ) secreted by CD8+ T cells?
What is one of the key functions of interferon-gamma (IFN-γ) secreted by CD8+ T cells?
What is the primary function of the thymus in relation to T-cells?
What is the primary function of the thymus in relation to T-cells?
What role do antigen-presenting cells (APCs) play in T cell activation?
What role do antigen-presenting cells (APCs) play in T cell activation?
Which of these lymphocyte types is specifically involved in humoral immunity?
Which of these lymphocyte types is specifically involved in humoral immunity?
Which type of lymphocytes is primarily responsible for producing antigen-specific antibodies?
Which type of lymphocytes is primarily responsible for producing antigen-specific antibodies?
What distinguishes cell-mediated immunity from humoral immunity?
What distinguishes cell-mediated immunity from humoral immunity?
What is the normal range of lymphocytes in the blood?
What is the normal range of lymphocytes in the blood?
Which cell surface proteins are crucial for presenting bits of cell contents for immune identification?
Which cell surface proteins are crucial for presenting bits of cell contents for immune identification?
In humans, which HLA group is not associated with MHC-I?
In humans, which HLA group is not associated with MHC-I?
What is the role of MHC-I when a cell is infected?
What is the role of MHC-I when a cell is infected?
How do T lymphocytes contribute to immunity?
How do T lymphocytes contribute to immunity?
What percentage of lymphocytes in the blood are T lymphocytes?
What percentage of lymphocytes in the blood are T lymphocytes?
What is a defining characteristic of lymphocytes compared to neutrophils?
What is a defining characteristic of lymphocytes compared to neutrophils?
Which type of immunity do Natural Killer (NK) cells belong to?
Which type of immunity do Natural Killer (NK) cells belong to?
What is the primary role of B-lymphocytes in the immune response?
What is the primary role of B-lymphocytes in the immune response?
What two signals are required for the activation of T-cells?
What two signals are required for the activation of T-cells?
In what locations do T-cells undergo positive and negative selection?
In what locations do T-cells undergo positive and negative selection?
What secretory characteristic is notable in plasma cells?
What secretory characteristic is notable in plasma cells?
What does central tolerance test B-cells for before they leave the bone marrow?
What does central tolerance test B-cells for before they leave the bone marrow?
What type of MHC molecules do B cells express?
What type of MHC molecules do B cells express?
What is the consequence of the random generation of B cell receptors?
What is the consequence of the random generation of B cell receptors?
What indicates a longer period since infection when examining antibodies in blood?
What indicates a longer period since infection when examining antibodies in blood?
What is the apoptotic mechanism's role in B cell development?
What is the apoptotic mechanism's role in B cell development?
How many molecules of a single antibody does a B cell typically have on its surface?
How many molecules of a single antibody does a B cell typically have on its surface?
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Study Notes
Innate Immune Cells
- Macrophages and granulocytes are key innate immune cells.
- Neutrophils, eosinophils, basophils, mast cells, dendritic cells, and NK (Natural Killer) cells are also included in this category.
- Innate immune response features: fast, non-specific, and generic.
Function of Innate Immune Cells
- Phagocytosis: Involves macrophages, neutrophils, and eosinophils to engulf and digest pathogens.
- Immunological Surveillance: NK cells monitor for abnormal cells.
- Physical Barriers: Skin, epithelial membranes, hair, and one-way urine flow act as initial defenses.
- Natural Antimicrobial Substances: Include HCl, lysozyme, natural antibodies, saliva, interferons, and complement proteins.
Inflammation
- Four classic signs of inflammation: rubor (redness), calor (heat), dolor (pain), tumor (swelling).
Adaptive Immune Cells
- Adaptive immune response depends on highly specialized cells: T lymphocytes and B lymphocytes.
- B lymphocytes are responsible for humoral immunity by producing antigen-specific antibodies, while T lymphocytes facilitate cell-mediated immunity.
Specificity of Adaptive Immunity
- Unique to specific antigens and establishes immunological memory for faster responses upon re-exposure.
- Lymphocytes possess large, round nuclei and are slightly smaller than neutrophils.
Lymphocyte Characteristics
- Normal lymphocyte count: 1.5-3.5 x 10^9/L.
- Lifespan of lymphocytes can extend for many years.
- Lymphocytes are divided into T-cells and B-cells, with T-cells comprising about 75% of circulating lymphocytes.
Role of Major Histocompatibility Complex (MHC)
- MHC molecules allow immune cells to distinguish self from non-self.
- MHC-I presents intracellular material and is found on all nucleated cells.
- MHC-II is present on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B-cells.
- Human leukocyte antigen (HLA) gene encodes MHCs, with three main groups: HLA-A, HLA-B, HLA-DR.
T Lymphocyte Function
- T helper cells (CD4+) bind to MHC-II for recognition and activation.
- Cytotoxic T cells (CD8+) bind to MHC-I, recognize infected cells, and induce apoptosis through perforin and interferon-gamma (IFN-γ).
B Lymphocyte Function
- B lymphocytes (produced in bone marrow) mount specific immune responses by secreting antibodies.
- Antibodies neutralize toxins, opsonize pathogens for phagocytosis, and activate the complement system.
- Memory B cells confer long-term immunity and produce high-affinity antibodies upon re-exposure.
Development of T-cells
- Thymocytes undergo positive selection (functional receptor) in the cortex and negative selection (removing self-reactive cells) at the cortex-medulla border.
- About 95-98% of thymocytes undergo apoptosis before reaching maturity.
Antibody Production and Action
- Plasma cells secrete up to 2000 antibodies per second and produce various antibody types, including IgM and IgG.
- Antibody functions include:
- Opsonization: Enhances phagocytosis.
- Complement Activation: Leads to lysis and enhances phagocytosis.
- Neutralization: Prevents the action of toxins and pathogens.
True/False Statements
- B-cells have CD19 on their surface - true.
- Plasma cells can secrete up to 200 antibodies per cell per second - false, it’s 2000.
- Antibodies defend the body through complement activation, opsonization, and neutralization - true.
Summary of Immune Response Types
- Cell-mediated response (T-cells): Protects against intracellular organisms.
- Humoral response (B-cells): Plasma cells release antibodies to defend against extracellular threats.
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