Immunology Quiz on Innate Immune Response

Immunology and Immunodiagnostic Methods

• Barriers to Infection (Step 1): Block infection using antimicrobial chemicals in tears, normal microflora in digestive/respiratory tracts, mucus, urinary flow, skin, and stomach acid.
• Infection (Step 2): If Step 1 is unsuccessful, infection occurs.
• Immune System Defense (Step 2):
  • Innate Immunity: The first line of defense, acting from the start of an infection.
    • Phagocytosis is the key action.
    • It recognizes patterns (amino acids, proteins) on pathogen surfaces but does not adapt to pathogens.
  • Adaptive Immunity: An antigen-specific response from B and T lymphocytes, creating immunological memory.
• Immunology Terms:
  • Antigen: Anything triggering an immune response (binds to immunoglobulin or T cell receptor).
  • Pathogen: Microorganism causing disease.
  • Immunoglobulin: Antigen-binding protein made by B cells.
  • Antibody: Secreted immunoglobulin.
  • Vaccination: Deliberate induction of protective immunity against pathogens.
  • Inflammation: A multi-step physiological response aiding innate immunity (can be localized or systemic).

Components of the Innate Immune System

• Phagocytic cells: All cells involved in the innate immune response have phagocytic ability. These include dendritic cells, neutrophils, and macrophages.
• Complement proteins: A key component of innate immunity.
• Native defense cytokines: Critical components of the immune response.
• Natural killer (NK) cells: Destroy cancer cells and cells with intracellular pathogens.
• Antimicrobial peptides: Help combat pathogens.
• Leukocytes (WBCs): Include lymphocytes for adaptive immunity and other specialized cells.
  • Lymphocytes: Originate in bone marrow and mature in primary lymphoid organs (bone marrow for B cells, thymus for T cells).
• Serum and Plasma: Fluid components of blood, with plasma containing clotting factors.
• Erythrocytes (RBCs): Red blood cells
• Buffy coat: Contains platelets and leukocytes.
• Leukocytes (types): Neutrophils (neutral dyes), eosinophils (pink), basophils (pink), and lymphocytes.

Lymphatic System

• Lymphatic System: A separate circulatory system that drains lymph fluid from tissues. Helps detect and fight pathogens.
• Lymph nodes: Structures filled with lymphocytes. Act as checkpoints, triggering immune responses upon detection of pathogens.

Immune cells

• Myeloid and Lymphoid cells: Derived from bone marrow stem cells, divided into categories of antigen-presenting cells (APCs) and granulocytes.
• APCs: Engulf and process antigens, presenting them to lymphocytes; include monocytes, macrophages, and dendritic cells.
• Granulocytes: Including neutrophils, basophils, and eosinophils; release toxins or enzymes to kill targeted cells.

Phagocytosis

• Phagocytosis: The process by which phagocytes engulf and destroy pathogens using lysosomes and amoeboid action.
• Types of phagocytes: Neutrophils (actively mobile granulocytes), monocytes (precursors of macrophages), and dendritic cells (antigen presentation).
• Steps in phagocytosis: Pathogen engulfing, pathogen digestion, and antigen presentation.
• Phagocytic killing abilities: Using toxic oxygen to kill infected bacteria.
• Pathogen Evasion techniques: Pathogens use various strategies to resist or evade phagocytic killing, including neutralizing toxic products, inhibiting phagocytes, or forming protective capsules..

Inflammation

• Inflammation: A nonspecific reaction to noxious stimuli; Symptoms include redness, swelling, pain, and heat.
• Molecular mediators: Chemokines and cytokines; they trigger the inflammatory response, help localize the damage, destroy damaged cells, and isolate pathogens.
• Steps of inflammation: Neutrophils arrive at the infection site, attracted by interleukins. Neutrophils release chemokines to attract macrophages.
• Cytokines: Help in cellular communication and regulate immune responses.
• Chemokines: Attract leukocytes.

Antibody diversity

• Mechanism of antibody diversity: Somatic recombination, hypermutation, and gene rearrangements of immunogenic cells.
• Opsonization: The process by which antibodies mark pathogens for phagocytosis, targeting and destroying them more effectively.
• Complement: Proteins that work in conjunction with antibodies to enhance the immune response. Complement activation achieves this through different pathways.
• Neutralization: Antibodies binding to toxins or pathogens, blocking their ability to harm cells.
• Agglutination: Antibodies sticking pathogens together, helping to isolate and destroy them.

Antibody

• Immunoglobulin G (IgG): The most common antibody in the bloodstream, exhibiting an important role in various immune responses.
• Immunoglobulin M (IgM): The first antibody class secreted in response to an initial immune stimulation.
• Immunoglobulin A (IgA): A critical antibody type for the protection of mucosal surfaces within the body.
• Immunoglobulin D (IgD): An immunoglobulin with a crucial role in the activation of B cells.
• Immunoglobulin E (IgE): A primary antibody in allergic reactions and parasite infections.

Antibody diversity Mechanisms

• Somatic Recombination: Unique mechanism for generating diverse antibody structures, by rearranging genes in B cells.
• Hypermutation: Further enhances antibody diversity. Gene rearrangements occur during B cell activation, leading to increased diversity.

Immunology Testing

• In Vitro Antigen-Antibody Reactions (Serology): In-vitro tests to study antigen-antibody interactions; methods include precipitation reactions, neutralization, and agglutination.
• Immunoblot/Western Blots: Detect antibodies or antigens via electrophoresis and antibody binding to specific target on a membrane.
• AGID (Agar Gel Immunodiffusion) Allows for detection of antigens by antibody-antigen binding, producing a visible complex.
• ELISA Enzyme-linked immunosorbent assay: Measures antibodies or antigens in a sample; a sensitive method for pathogen detection and diagnostics.

Immunity Types

• Adaptive Immunity: Acquired ability to recognize and destroy pathogens, only triggered by prior exposure, involves T cells and B cells.
• Innate Immunity: First line of defense, including phagocytes, complement proteins, antimicrobial peptides, and other components of the immune system.

Immunization

• Artificial and natural forms of active and passive immunity.

Vaccination Protocols

• Types of vaccines: Live attenuated vaccines, killed vaccines, subunit vaccines, DNA vaccines, live vector vaccines, and conjugate vaccines.
• Vaccine administration routes: Subcutaneous, intramuscular, intradermal, intranasal, and oral methods.
• Herd immunity: Achieving resistance to disease in a population where a high percentage of people are immune to the disease.
• Booster shots: Additional doses of vaccine to enhance or maintain immunity and strengthen immune response.

Viral Diseases

• Rabies: Causes neurological signs, often lethal, transmitted through animal bites.
• Bovine Spongiform Encephalopathy (BSE): Similar to Creutzfeldt-Jakob disease; fatal neurological disease that can be transmitted when consuming contaminated cattle products.
• Canine Parvovirus: Very unstable, leading to the evolution of new strains; infects the intestines, causing severe illness in dogs.
• Feline Panleukopenia Virus (FPLV): Retrovirus affecting cats, leading to immunosuppression.

Other Diseases

• West Nile Virus: Viral encephalitis transmitted through mosquito bites, affecting the nervous system.
• Ehrlichiosis: Caused by bacteria that infect cells, and can be zoonotic.
• Vesicular Stomatitis Virus: Primarily impacts cloven-hoofed animals, causing blisters on the skin.
• Toxo/Parasites: Harmful microorganisms, including protozoans and other infectious agents with diverse effects.
• Cryptosporidiosis: Intestinal protozoan that sometimes causes severe diarrhea.
• Fungal Diseases: Mycoses, like athlete's foot, that are caused by fungal microorganisms.