MCB2000 Exam 4 Study Guide

Non-Specific Immunity

  • Elements involved:

    • Physical barriers:

    • Skin: Acts as a protective barrier against pathogens.

    • Mucous membranes: Trap pathogens and debris; contain antimicrobial substances.

    • Chemical barriers:

    • Lysozyme: Enzyme found in saliva and tears that breaks down bacterial cell walls.

    • Sweat: Contains salts and antimicrobial substances.

    • Stomach acid: Destroys pathogens ingested with food.

    • Cellular defenses:

    • Phagocytes, such as neutrophils and macrophages: Engulf and digest pathogens.

    • Natural Killer (NK) cells: Destroy virus-infected cells and tumor cells.

    • Inflammation:

    • Localized tissue response to injury or infection, characterized by redness, heat, swelling, and pain.

    • Fever:

    • Elevated body temperature that enhances the immune response.

    • Complement system:

    • A group of serum proteins that assist in the destruction of pathogens.

Blood Component Origin

  • Origin:

    • All blood components originate from hematopoietic stem cells found in the red bone marrow.

MHC Proteins

  • Definition:

    • MHC = Major Histocompatibility Complex; membrane glycoproteins that present antigens to immune cells.

  • Types & functions:

    • MHC I:

    • Present on all nucleated cells.

    • Displays endogenous antigens to CD8 T cells.

    • MHC II:

    • Found only on Antigen-Presenting Cells (APCs) such as macrophages, dendritic cells, and B cells.

    • Presents antigens to CD4 T helper cells.

  • Significance:

    • Distinguishes between self and non-self, facilitating adaptive immune responses.

Differences Between B Cells and T Cells

  • B Cells:

    • Different forms:

    • Naive B cells: Unactivated state.

    • Activated B cells: Triggered by antigen.

    • Plasma cells: Secrete antibodies.

    • Memory B cells: Provide long-term immunity.

    • Functions:

    • Produce antibodies against pathogens.

    • Recognize native antigens.

  • T Cells:

    • Types:

    • Cytotoxic T cells (CTLs) and T helper cells (Th cells).

    • Functions:

    • Do not produce antibodies; they mediate Cell-Mediated Immunity (CMI).

    • Require antigen presentation via MHC molecules.

Cytokines and Interferons

  • Cytokines:

    • Signaling proteins that mediate and regulate immune responses.

    • Examples:

    • Interleukin-1 (IL-1), Tumor Necrosis Factor (TNF), Colony Stimulating Factors (CSFs).

  • Interferons (IFNs):

    • Types:

    • IFN-α, IFN-β, IFN-γ.

    • Functions:

    • Inhibit viral replication and activate various immune cells.

Complement Proteins

  • Definition:

    • A series of serum proteins activated through classical, alternative, or lectin pathways.

  • Functions:

    • Membrane Attack Complex (MAC): Causes lysis of pathogens.

    • Opsonization: Enhances phagocytosis (via C3b).

    • Inflammation: Promotes chemotaxis (via C5a).

Definitions of Blood Components

  • Lymphocytes:

    • Include B cells, T cells, and NK cells.

  • Leukocytes:

    • All white blood cells (WBCs): neutrophils, eosinophils, basophils, monocytes, lymphocytes.

  • Erythrocytes:

    • Red blood cells (RBCs).

Active vs Passive Immunization

  • Active Immunization:

    • The body produces its own B/T cells in response to infection or through vaccines.

  • Passive Immunization:

    • The body receives pre-formed antibodies.

    • Examples:

    • Antitoxins, maternal IgG transferred across placenta, and IgA in breast milk.

Uses of ELISA Test

  • Practical Uses:

    • Detect the presence or levels of antigens and antibodies, such as:

    • HIV p24 antigen, viral proteins, HIV antibodies, hepatitis, COVID-19.

    • Commonly used in diagnostics, pregnancy tests for hCG variants, and various screening assays.

Natural vs Artificial Immunity

  • Natural Immunity:

    • Natural active: Acquired through infection.

    • Natural passive: Acquired through maternal antibodies.

  • Artificial Immunity:

    • Artificial active: Acquired through vaccines.

    • Artificial passive: Acquired through injected antibodies, e.g., anti-venom.

Cell-Mediated vs Humoral Immunity

  • Cell-Mediated Immunity (CMI):

    • Major components: T helper cells, cytotoxic T cells, NK cells.

    • Function: Destroys intracellular pathogens and cancer cells.

  • Humoral Immunity:

    • Major components: B cells, plasma cells, antibodies.

    • Function: Neutralization of pathogens, opsonization, and complement activation.

Antibody Structure

  • Components:

    • Composed of two heavy and two light chains.

  • Regions:

    • Fab region: Binds antigen.

    • Fc region: Binds immune cells and complement proteins.

Opsonization

  • Definition:

    • The process of coating pathogens to enhance phagocytosis.

  • Opsonins:

    • Include IgG and C3b.

Hypersensitivity

  • Definition:

    • An exaggerated immune response that causes tissue damage.

  • Types:

    • Type I: IgE-mediated hypersensitivity (e.g., allergies, anaphylaxis).

    • Type II: IgG/IgM cytotoxic hypersensitivity (e.g., ABO reactions, Rh/HDN).

    • Type III: Immune complex-mediated hypersensitivity (e.g., lupus, serum sickness).

    • Type IV: T-cell mediated hypersensitivity (e.g., TB test, poison ivy).

Immunodeficiency Definition

  • Primary Immunodeficiency:

    • Genetic defects leading to immunological weaknesses (e.g., SCID, DiGeorge syndrome, Bruton's agammaglobulinemia).

  • Secondary Immunodeficiency:

    • Acquired conditions affecting immunity (e.g., AIDS, cancer, malnutrition, drugs).

    • True: Viral infections can lead to secondary immunodeficiency.

Vaccine Types and Safety

  • Types:

    • Live attenuated vaccines: Weakened pathogens.

    • Killed/inactivated vaccines: Pathogens killed by heat/chemicals.

    • Subunit vaccines: Purified antigens only.

    • Recombinant vaccines: Genetically engineered components.

    • Toxoid vaccines: Inactivated toxins (e.g., tetanus).

    • Conjugate vaccines: Polysaccharide linked to protein for enhanced children response.

    • Virus-Like Particle (VLP) vaccines: Mimic virus structures.

    • Nucleic acid vaccines: DNA and mRNA vaccines.

  • Safety:

    • Adverse reactions may occur, but vaccines undergo extensive testing; adjuvants are added to boost immune response.

Comparison of Killed vs Live Attenuated Vaccines

  • Killed:

    • Safer but may require boosters, primarily induce humoral immunity.

  • Live Attenuated:

    • Stronger and longer-lasting immune response, inducing both CMI and humoral immunity.

Dry Vaccines and Adjuvants

  • Dry Vaccines:

    • (e.g., Nanopatch): Deliverable in dry form directly to skin; no refrigeration required.

  • Adjuvants' Role:

    • Enhance the immune response (examples include alum and MPL).

Vaccine-Preventable Diseases

  • Impact:

    • Diseases like diphtheria, polio, measles have seen dramatic reductions due to vaccination efforts.

    • Outbreaks occur where vaccination rates are low, with ongoing global eradication initiatives.

Immunity Types

  • Definitions:

    • Active Immunity: Body produces its own antibodies.

    • Passive Immunity: Receives pre-formed antibodies.

    • Natural Immunity: Developed through infection or maternal antibodies.

    • Artificial Immunity: Developed through vaccines or antibody injections.

Lymphoid Organs

  • Primary Lymphoid Organs:

    • Bone marrow, thymus: sites for lymphocyte development.

  • Secondary Lymphoid Organs:

    • Lymph nodes, spleen, MALT (Mucosal-Associated Lymphoid Tissue), BALT (Bronchus-Associated Lymphoid Tissue), GALT (Gut-Associated Lymphoid Tissue), SALT (Skin-Associated Lymphoid Tissue): trap antigens at mucosal sites.

Primary vs Secondary Immune Response

  • Primary Immune Response:

    • Slow to develop, first antibody type is IgM, generally low titer.

  • Secondary Immune Response:

    • Rapid and larger response, dominated by IgG, involving memory cells.

Defense Lines

  • First Line:

    • Skin, mucous membranes, normal flora.

  • Second Line:

    • Phagocytic cells, inflammation, fever, complement system.

  • Third Line:

    • Antibodies, T cells, memory cells.

Phagocytic Cells and APCs

  • Phagocytic Cells:

    • Include macrophages, neutrophils, dendritic cells.

  • APCs (Antigen-Presenting Cells):

    • Macrophages, dendritic cells, B cells present antigens via MHC II.

Antigens

  • Definition:

    • Substances that trigger an immune response.

  • Most Antigenic Molecules:

    • Proteins (most antigenic), polysaccharides, followed by lipids and nucleic acids, which are weak unless conjugated.

Phagocytosis Mechanism

  • Lysosome:

    • Organelle containing degradative enzymes for breaking down pathogens.

  • Phagosome:

    • Vesicle that contains the engulfed microbe.

  • Fusion Process:

    • Lysosome fuses with phagosome forming a phagolysosome where the microbe is killed by enzymes and toxic oxygen species.

Degranulation

  • Definition:

    • The release of granules from mast cells, basophils, and eosinophils.

  • Example of Granules:

    • Histamine, leukotrienes, prostaglandins.

Bone Marrow Transplant Cells

  • Transplanted Cells:

    • Hematopoietic stem cells, which are immune progenitors.

Immunoglobulin Types

  • Comparison:

    • IgG: Main antibody found in blood and extracellular fluid; important for immune response.

    • IgM: First antibody produced during an immune response.

    • IgA: Found in mucous membranes, saliva, tears, and breast milk.

    • IgE: Associated with allergic reactions and responses to parasitic infections.

Function of Immune Cells

  • Eosinophils:

    • Combat parasites and respond in allergy.

  • Cytotoxic T cells (Tc):

    • Kill infected host cells directly.

  • Natural Killer Cells (NK):

    • Attack cells lacking MHC I to eliminate harmful cells.

  • T Helper Cells (Th):

    • Activate B cells, T cells, and macrophages to enhance immune response.

Plasma Cells vs Memory B Cells

  • Plasma Cells:

    • Short-lived and secrete antibodies.

  • Memory B Cells:

    • Long-lived cells that provide a rapid response during subsequent exposures.

Rh Factor and Hemolytic Disease

  • Relationship:

    • When an Rh-negative mother carries an Rh-positive fetus, the mother may develop anti-Rh IgG antibodies.

    • In subsequent pregnancies, IgG may cross the placenta and lead to fetal hemolysis (Type II hypersensitivity reaction).

Interpreting Blood Cell Counts

  • High Neutrophils:

    • Suggests bacterial infection.

  • High Eosinophils:

    • Indicates allergy or parasitic worm infection.

  • High Interferons:

    • Suggests viral infection.

Antigen Presenting Cells (APCs)

  • Definition:

    • Cells that present antigens via MHC II to T cells.

  • Examples of APCs:

    • Dendritic cells, macrophages, B cells.

Inflammation and Diapedesis

  • Inflammation:

    • A nonspecific reaction to injury characterized by redness, heat, swelling, pain, and loss of function.

  • Diapedesis:

    • Process by which white blood cells squeeze out of blood vessels into tissues.

Host vs Graft and Graft vs Host Reactions

  • Host vs Graft:

    • Host’s T-cells attack transplanted tissue due to perceived foreignness.

  • Graft vs Host:

    • Donor immune cells attack host tissues (common in bone marrow transplants).

Hematopoietic Cells

  • Definition:

    • Blood-forming stem cells found in the bone marrow responsible for the production of blood cells.

Myeloid vs Lymphoid Cells

  • Myeloid Cells:

    • Include neutrophils, eosinophils, basophils, monocytes, and macrophages.

  • Lymphoid Cells:

    • Include B cells, T cells, and NK cells.

Fever Production

  • How Fever is Produced:

    • Pyrogens such as IL-1 and bacterial toxins signals the hypothalamus to increase body temperature.

Allergic Reactions

  • Involved Antibody:

    • IgE plays a significant role in mediating allergic responses.

  • Chemicals Involved:

    • Allergens can include pollen, nuts, latex, and dust mites.

  • Desensitization:

    • Involves exposure to increasing doses of allergen to induce IgG (“blocking antibody”).

Immunosuppressive Drugs

  • Purpose:

    • Prevent graft rejection and limit autoimmune reactions.

Systemic Anaphylaxis

  • Description:

    • A systemic IgE-mediated response leading to massive mediator release, causing vasodilation and potentially shock; epinephrine is required for treatment.

Neutralization in Viral Infections

  • Role:

    • Antibodies block viral binding to host cells, thus preventing infection; they also neutralize toxins produced by pathogens.

Autoimmunity

  • Definition:

    • An immune response against self-antigens.

  • Examples:

    • Multiple Sclerosis (MS affecting myelin), Lupus (immune complexes), Rheumatoid Arthritis (affecting joints).

Phagocytic Failure Examples

  • Causes of Failure:

    • Bacterial capsules, toxin production, prevention of phagosome-lysosome fusion, and the killing of phagocytes (e.g., leukocidins).

ELISA Test Functionality

  • How ELISA Works:

    • Involves antigen-antibody binding and enzyme color change to identify antigens or antibodies.

    • Provides both quantitative and qualitative data on the presence of antigens or antibodies.

Desensitization Mechanism

  • Mechanism:

    • Involves repeated low-dose exposure to allergens that increases IgG levels while decreasing IgE responses.

Antigen-Antibody Interaction Outcomes

  • Possible Outcomes:

    • Neutralization, opsonization, complement activation, inflammation, agglutination, and precipitation.

Preventing Viral Attachment

  • Neutralization:

    • Antibodies that block viral attachment to host cells also prevent damage from toxins.

Diagnostics Tests Defined

  • Tests:

    • Precipitation Test: A visible line appears when soluble antigen binds to antibody.

    • Agglutination Test: Particulate antigens cause clumping of cells, as seen during blood typing.

    • Neutralization Test: Antibodies block access of toxins or viruses to target cells.

    • Fluorescent Antibody (FA) Test: Uses fluorescently labeled antibodies to detect specific antigens or antibodies.

Chemotherapeutic Agents

  • Definition:

    • Chemicals used to treat diseases, including antimicrobials.

Ideal Antimicrobial Drug Characteristics

  • Desired Features:

    • High selective toxicity, chemical stability, low side effects, minimal risk for resistance development, ability to reach the infection site effectively.

Natural vs Semisynthetic Antibiotics

  • Natural Antibiotics:

    • Produced directly by microorganisms, often to compete with other microbes.

  • Semisynthetic Antibiotics:

    • Chemically modified derivatives of natural antibiotics to enhance efficacy or decrease side effects.

Antimicrobial Agents' Action Sites

  • Targets:

    • Cell wall, cell membrane, protein synthesis, DNA/RNA synthesis, and critical metabolic pathways.

β-lactam Ring

  • Definition and Examples:

    • Essential ring structure for antibiotic activity, found in drugs like penicillins and cephalosporins.

Selectivity of Ribosome Targeting

  • Ribosome Differences:

    • Bacterial 70S ribosomes are different from eukaryotic 80S, allowing for selective targeting of bacterial protein synthesis without harming human cells.

Antibiotic-Producing Microorganisms

  • Produced By:

    • Soil bacteria (e.g., Streptomyces, Bacillus) and fungi (e.g., Penicillium), which produce antibiotics to inhibit competition from other microbes.

Mechanisms of Action of Antibiotics

  • Categories and Examples:

    • Cell Wall Synthesis Inhibitors:

    • Penicillins, cephalosporins, vancomycin.

    • Protein Synthesis Inhibitors:

    • Tetracyclines, streptomycin, erythromycin.

    • DNA Replication Inhibitors:

    • Ciprofloxacin.

    • RNA Synthesis Inhibitors:

    • Rifampin.

    • Membrane Disruptors:

    • Polymyxins, amphotericin B (used against fungal infections).

Drug Synergy Example

  • Combination Actions:

    • Sulfa drugs + Trimethoprim: Inhibit the folic acid synthesis pathway creating a synergistic effect against bacteria, effective due to the fact that humans do not synthesize folic acid.

DNA Damage Mechanism by Radiation

  • Types of Radiation:

    • UV Radiation: Causes thymine dimers in DNA.

    • X-rays/Gamma Rays: Cause breaks in DNA strands.

Selective Toxicity Challenges

  • Definition:

    • The ability to target pathogens while causing minimal harm to the host; more challenging with antivirals due to viruses using host cellular machinery and with antifungals due to fungi being eukaryotic.

Mechanisms of Microbial Drug Resistance

  • Resistance Strategies:

    • Efflux pumps, drug inactivation (e.g., β-lactamase), altered drug targets, decreased permeability to drugs, and alternative metabolic pathways.

  • Gene Spread Methods:

    • Through mechanisms such as conjugation, transduction, transformation, and transposons.

Antifungal and Antiviral Drug Mechanisms

  • Antifungal Examples and Mechanisms:

    • Amphotericin B: Binds to ergosterol in fungal cell membranes.

    • Azoles: Inhibit ergosterol synthesis.

    • Griseofulvin: Interferes with microtubule function.

  • Antiviral Examples and Mechanisms:

    • Acyclovir: Guanosine analogue that inhibits viral DNA synthesis.

    • Tamiflu: Neuraminidase inhibitor that prevents the release of influenza virus.

Modes of Action of Antiviral Drugs

  • Actions:

    • Block entry/fusion of viruses, uncoating, genome replication, reverse transcription, protease activity, and viral release prevention.

Anti-HIV and Flu Drug Mechanisms

  • HIV Drugs:

    • Reverse transcriptase inhibitors and protease inhibitors that halt viral proliferation.

  • Flu Drugs:

    • Tamiflu prevents neuraminidase's action to block viral release from infected cells.

Physical Barriers of the Immune System

  • Skin and Mucous Membranes:

    • Skin: Provides a physical barrier, contains keratin, lysozyme, and has a low pH to prevent pathogen entry.

    • Mucous Membranes: Employ the mucociliary escalator and mucus trapping to eliminate pathogens, as well as secrete antimicrobial peptides.

Multiple Choice Questions (MCQs) Guidance

  • Example MCQs discussing various topics including:

    • Targets of antibiotics, immunity response mechanisms, and antibody function applications.

    • Understanding results from drug resistance and immunological principles enforce learning outcomes related to coursework.

Cell Sorting Technology

  • FACS (Fluorescence-Activated Cell Sorting):

    • Sorts cells based on size and fluorescence for separating specific immune cell populations, aiding in research and diagnostics.

Hybridomas in Monoclonal Antibody Production

  • Role of Hybridoma:

    • Formed by fusing myeloma cells with antibody-producing B cells, resulting in an immortal cell line that produces a specific monoclonal antibody for targeted therapeutic applications.

Additional Information

  • More questions may be included for further review and study purposes.