Immunology Flashcards
Lecture 1:
Who is considered the pioneer of vaccination, and what disease did he target?
Edward Jenner is considered the pioneer of vaccination; he targeted smallpox using cowpox pus.
What major concept in immunology did Elie Metchnikoff describe and name?
Elie Metchnikoff described and named phagocytosis, the ingestion of foreign matter by white blood cells.
What are the two primary arms of adaptive immunity?
Humoral immunity (antibody production by B cells) and cell-mediated immunity (T cells killing infected cells and aiding other immune cells).
What are the main cells involved in natural immunity?
Granulocytes (Neutrophils, Eosinophils, Basophils), Monocytes, and Natural Killer (NK) cells.
Define ‘antigen’ and list its key characteristics.
An antigen is a substance recognized as foreign by the immune system, provoking a response. Key characteristics include immunogenicity (ability to provoke an immune response) and reactivity (ability to react with antibodies or T cells).
What is the primary function of the complement system in immunity?
The complement system aids in pathogen elimination and links innate and adaptive immunity through a cascade of protein reactions.
What are the four properties of specific immunity, often referred to as the 4 Rs?
Recognition (identifying foreign antigens), Response (eliminating the antigen), Remember (memory of the antigen for quicker future response), and Regulate (reducing the immune response once the threat is diminished).
What are the phases of immune response to infection, and their time frames?
Innate Immunity: Immediate response (0-4 hours)
Early Induced Response: Activation of innate effectors (4-96 hours)
Adaptive Response: Activation of T and B cells, pathogen removal, and memory formation (>96 hours)
What is the significance of immunological memory in vaccination?
Immunological memory allows for long-term protection against diseases by leveraging the memory response developed after vaccination.
Describe Paul Ehrlich’s Side Chain Theory.
Paul Ehrlich’s Side Chain Theory, blood cells- bind and inactivate pathogens= antibody production.
Name the primary and secondary organs involved in the immune system.
Primary Organs: Bone marrow and thymus (formation and maturation of immune cells).
Secondary Organs: Lymphatic system and spleen (immune cells’ activity).
Differentiate between active and passive immunity.
Active immunity develops after exposure to a disease or vaccine, while passive immunity is transferred from another individual, such as from mother to fetus.
What were some of the major infectious diseases and their mortality rates? (Name at least 1)
AIDS: 2.6 million deaths per year
Infantile respiratory infections: 3.5 million
Infantile diarrhea: 2.2 million
Tuberculosis: 1.5 million
Malaria: 1.1 million
Lecture 2:
Name the main types of phagocytic cells involved in innate immunity.
Monocytes/macrophages and neutrophils.
What are the three types of epithelial barriers involved in innate protection?
Mechanical barriers (flow of air or fluid, movements of mucus), chemical barriers (fatty acids in skin, lysozyme in saliva and tears, pepsin in the gut), and microbiological barriers (commensal bacteria).
What is the importance of Mucosal-Associated Lymphoid Tissue (MALT)?
It is the principal site for infections and allergic reactions, serves as an absorptive surface for food and oxygen, acts as a barrier against antigen penetration, and responds to antigens.
What role do commensal bacteria play in innate immunity?
They prevent adherence and penetration into the mucosa and are the main immune stimuli for neonates from microbial signals.
Define opsonization and name two types of opsonins.
Opsonization is the process by which pathogens are marked for ingestion and destruction by phagocytes. Two types of opsonins are immunoglobulins and complement protein fragments.
What are Pattern Recognition Receptors (PRRs) and what do they recognize?
PRRs are receptors that recognize pathogen-associated molecular patterns (PAMPs).
Name the types of PRRs and give one example of each.
Cellular: Scavenger receptors
Humoral: Collectins
Intracellular/Cytosolic: NOD-like receptors
Surface: Toll-like receptors (TLRs)
What are the functions of Toll-like Receptors (TLRs)?
TLRs bind to PAMPs, triggering immune responses such as cytokine production and inflammation.
List four examples of antimicrobial factors and their functions.
Salivary Peroxidase: Bactericidal effects
Lysozyme: Digests bacterial cell walls
Lactoferrin: Iron-binding to block bacterial growth
Histatins: Anti-fungal agents
What are antimicrobial peptides, and what is their mechanism of action?
Antimicrobial peptides are amphipathic cationic molecules that interact with membrane phospholipids to form pores in pathogens’ membranes.
What are the key functions of Natural Killer (NK) cells in innate immunity?
NK cells defend against viruses and tumors, produce interferon-gamma (IFN-γ), and contain perforin and granzymes for cell-mediated cytotoxicity.
Summarize the main characteristics of innate immunity.
Innate immunity is the first line of defense, versatile despite limited diversity, does not react against host cells, is activated only on microbial surfaces, and lacks immunological memory.
What are the main components of innate immunity?
Barriers (prevent microbial entry), circulating cells (neutrophils, macrophages, NK cells), and soluble factors (complement, mannose-binding lectin, C-reactive protein, cytokines).
Lecture 3:
What are the primary lymphoid tissues and their functions?
Bone Marrow: Produces all blood cell lineages including B cells.
Thymus: Site for T cell maturation.
What are the secondary lymphoid tissues and their functions?
Spleen and lymph nodes; sites for immune responses.
Describe the typical structure of immunoglobulin molecules.
Immunoglobulin molecules have two heavy chains and two light chains joined by disulphide bonds, with variable and constant regions.
What are the functions of IgM?
IgM is the first antibody produced, activates complement, and is too large to cross the placenta.
What role does IgG play in the immune system?
IgG is the most abundant immunoglobulin, can cross the placenta, and is involved in opsonization and complement activation.
What are the primary and secondary immune responses?
Primary Response: Slow, brief initial production of IgM followed by IgG.
Secondary Response: Rapid, longer-lasting, mainly IgG, with higher affinity due to affinity maturation.
What are the two types of B cell activation?
T-Independent Activation: Bacterial endotoxins trigger IgM production.
T-Dependent Activation: Requires help from T-helper cells for B cell proliferation and antibody secretion leading to memory formation.
How do B lymphocytes differ from T lymphocytes?
B Lymphocytes: Produce antibodies, mainly effective against extracellular infections.
T Lymphocytes: Recognize antigens via T-cell receptors, involved in intracellular infection response.
What is class switching in immunoglobulins?
Class switching is the change of heavy chains in immunoglobulins while retaining antigen specificity.
What is somatic hypermutation and its significance?
Somatic hypermutation alters variable regions of immunoglobulins to improve antigen binding affinity.
Name and describe the specific functions of IgE.
IgE is involved in allergic responses and defense against parasites.
Where is IgA primarily found and what is its function?
IgA is found in mucosal areas and is involved in mucosal immunity.
What are the roles of immunoglobulins in the immune system?
Immunoglobulins act as adapter molecules that can activate complement, mediate phagocytosis, and trigger allergic reactions.
Lecture 4:
What are the three main types of T cells?
Cytotoxic T Cells (CD8+)
Helper T Cells (CD4+)
Regulatory T Cells
How do Helper T Cells (CD4+) assist in the immune response?
Helper T Cells assist in activating immune cells by recognizing antigens presented by MHC Class II molecules and producing cytokines.
What is the primary function of Cytotoxic T Cells (CD8+)?
Cytotoxic T Cells kill virus-infected and abnormal cells by inducing apoptosis.
What is the role of Regulatory T Cells?
Regulatory T Cells inhibit immune responses to prevent autoimmunity by producing cytokines like IL-10 and TGF-beta.
Where are T cells activated?
T cells are activated in secondary lymphoid tissues, such as lymph nodes and the spleen.
Describe the structure of T-cell receptors (TCR).
T-cell receptors have a similar structure to immunoglobulins but remain membrane-bound, consisting of constant and variable regions. They come in two forms: αβ (common) and γδ (less common).
What is antigen presentation?
Antigen presentation is the process by which protein fragments from pathogens or other foreign substances are displayed on the surface of cells by MHC molecules, allowing T cells to recognize and respond to the antigens.
Differentiate between MHC Class I and MHC Class II molecules.
MHC Class I: Present on all nucleated cells, present intracellular antigens to CD8+ T cells.
MHC Class II: Present on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells, present extracellular antigens to CD4+ T cells.
How are antigens processed in the MHC Class I pathway?
Intracellular antigens are processed in the endoplasmic reticulum and presented on the cell surface by MHC Class I molecules.
How are antigens processed in the MHC Class II pathway?
Extracellular antigens are processed in acidified endosomes and presented on the cell surface by MHC Class II molecules.
What mechanisms do Cytotoxic T Cells use to kill infected cells?
Cytotoxic T Cells induce apoptosis in infected cells using perforin, granzymes, and granulysin.
What is the role of Helper T Cells in activating macrophages and assisting B cells?
Th1 cells activate macrophages, while Th2 cells assist B cells in antibody production.
Explain the concept of MHC polymorphism and its significance.
MHC polymorphism refers to the high variability in MHC genes, allowing for a broad range of antigen presentation, which is essential for effective immune responses and complicates organ transplantation.
What is apoptosis, and why is it important in the immune response?
Apoptosis is programmed cell death used by cytotoxic T cells to eliminate infected cells without releasing pathogens, ensuring controlled cell death to prevent the spread of infections.
Define cytokines and their primary functions.
Cytokines are low molecular weight proteins secreted by immune cells to regulate immune responses, acting in autocrine, paracrine, and endocrine manners.
What are the properties of cytokines?
Cytokines are pleotropic, synergistic, and can have a cascade effect, meaning they have different effects depending on the target cell, work together to enhance effects, and one cytokine can stimulate the production of others.
Name and describe the cytokine families
Haematopoietin Family: IL-2, IL-4
Interferon Family: IFN-alpha, beta, gamma
Chemokine Family: Attracts cells to sites of infection
Tumor Necrosis Family: Involved in inflammation and cell death
What is the function of IL-2 and IL-4 cytokines?
IL-2: T cell growth factor.
IL-4: B cell growth factor.
What is the role of Interferon-gamma (IFN-γ)?
Interferon-gamma (IFN-γ) activates macrophages and has antiviral properties.
What are the effects of TNF-alpha cytokine?
TNF-alpha promotes inflammation and can kill cancer cells.
What can result from a cytokine imbalance?
Cytokine imbalance can lead to diseases such as cytokine storm, which involves excessive cytokine release causing multi-organ failure.
How do inflammatory cytokines contribute to sepsis?
Inflammatory cytokines like TNF-alpha, IL-1, and IL-6 contribute to the symptoms and severity of sepsis, leading to septic shock with poor blood perfusion, abnormal clotting, and organ dysfunction.
Summarize the primary functions of MHC-I and MHC-II molecules.
MHC-I: Presents intracellular antigens to CD8+ T cells.
MHC-II: Presents extracellular antigens to CD4+ T cells.
What is a cytokine storm, and what are its consequences?
A cytokine storm is an excessive cytokine release causing multi-organ failure and is often associated with severe infections and immune responses.
Name the three pathways that activate the complement system.
Classical Pathway
Lectin Pathway
Alternative Pathway
How is the Classical Pathway triggered?
The Classical Pathway is triggered by C1q binding to immune complexes (antigen-bound IgM or IgG).
What does the Classical Pathway produce that is crucial for its function?
It produces C3 convertase (C4b2a) which cleaves C3 into C3a and C3b, leading to the formation of C5 convertase (C4b2aC3b) and ultimately the Membrane Attack Complex (MAC) (C5b C6 C7 C8 C9).
What activates the Lectin Pathway?
The Lectin Pathway is activated by mannose-binding lectin (MBL) binding to pathogens.
What is the role of the alternative pathway in complement activation?
The Alternative Pathway is continuously active at a low level (“tick-over” mechanism) and is activated by pathogen surfaces.
What are the primary roles of the complement system?
Opsonization: C3b binds to pathogens marking them for phagocytosis.
Inflammation: C3a and C5a act as anaphylatoxins promoting inflammation.
Pathogen Lysis: MAC creates pores in pathogen membranes causing cell lysis.
