Immunology Quiz: Antibodies and Agglutination

Immunology and Immunodiagnostic Methods

• Barriers to Infection (Step 1): Block infection through antimicrobial chemicals in tears, normal microflora in tracts, mucus in respiratory tract, urinary flow, skin, and stomach acid.
• Infection (Step 2): If barriers fail, infection enters causing disease.
• Innate Immunity: First line of defense, acting immediately on infection, non-adaptive, phagocytic (engulfing pathogens).
• Adaptive Immunity: Specific lymphocytes responding to antigens, adaptive response, immunological memory through specific B or T lymphocytes.
• Immunological Terms:
  • Antigen: Triggers 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 immunity to a specific pathogen.

Components of the Innate Immune System

• Phagocytic cells: Dendritic cells, neutrophils, and macrophages have phagocytic ability.
• Leukocytes: Nucleated white blood cells. Lymphatic system consists of a separated circulatory system draining lymph fluid from extra vascular tissues. Lymphocytes, enter lymphatic system through capillary beds known as lymph nodes, these are checkpoints for pathogens. Myeloid cells which arise from myeloid precursor cells in bone marrow.
• Serum/Plasma: Cell-free liquid components of blood. Serum lacks clotting factors, and plasma contains clotting factors.
• Erythrocytes/RBCs: Red blood cells.
• Buffy coat: Contains platelets and leukocytes.
• Leukocytes: Neutrophils, eosinophils, basophils, lymphocytes.
• Monocytes: Phagocytic cells.
• Lymphatic System:
  • Transports lymph fluid.
  • Lymph nodes filter lymph fluid.
  • Contain high concentrations of lymphocytes and phagocytes.
• Immune Cells:
  • Myeloid cells - Antigen presenting cells(APCs) and Granulocytes
    • APCS: Monocytes, macrophages, dendritic cells.
    • Granulocytes - Neutrophils, basophils, eosinophils.
  • Lymphocytes - Specialized Leukocytes (Adaptive Immune response).
    • Originate in bone marrow.
    • Mature in primary lymphoid organs (B cells in bone marrow and T cells in thymus)
• Phagocytosis: Process where phagocytes engulf and destroy pathogens. Uses lysosomes (intracellular vesicles which contain enzymes that aid in digestion), move by amoeboid action. Process includes initial engulfment of the pathogen, pathogen digestion inside vesicles from Golgi, and presentation using MHC of the digested fragment.
• Phagocytes:
  • Neutrophils: Actively mobile granulocytes found in blood circulation.
  • Monocytes: Larger cells found in lymph nodes and spleen. Serve as precursors of macrophages (localized to specific tissues).
  • Dendritic cells: Antigen presenting cells that move to Lymph nodes to present the antigen to T cells. They are found in the blood circulation and in specific tissues.
• Pathogen Evasion Techniques: Some pathogens do escape phagocytosis and cause disease (e.g., S. aureus and M. tuberculosis).
• Complement Proteins: Crucial for innate and adaptive immunity (inflammation). They can directly lyse pathogens and aid in phagocytosis.

Inflammation

• Symptoms: Redness, swelling, pain, and heat.
• Molecular Mediators: Chemokines and cytokines.
• Effective Inflammation: Localizes damage and destroys pathogens.
• Widespread Inflammation (Septic Shock): Failure to localize pathogens, very dangerous situation.
• Steps: Neutrophils arrive first, attracted by interleukins, move to infection sites (diapedesis), and trigger more macrophages.

Immune Response Cells

• Myeloid cells: From myeloid precursor cells in bone marrow.
• Granulocytes: Contain toxins that kill targeted cells.
• Immune cell flow chart: Illustrates the pathways and interrelationships of different immune cells.

Phagocytosis

• Mediated by phagocytes: Recognising pathogens using pattern recognition receptors (PRRs).

Antibody Diversity

• Mechanism: Unique to T and B cells. Includes somatic recombination, hypermutation, and gene rearrangement.

Modes of action for antibodies

• Opsonization: Pathogen is marked for phagocytosis. Antibody markers bind to phagocytic receptors.
• Neutralization: Toxin is bound preventing it from binding to the cell.
• Agglutination: Viral components bound together, preventing binding to host cells.

Antibody types

• Immunoglobulin G (IgG): Most common circulating antibody.
• Immunoglobulin M (IgM): First antibody secreted in adaptive immune response, good at agglutination.
• Immunoglobulin A (IgA): Protects mucous membranes.
• Immunoglobulin E (IgE): Found in serum and binds to eosinophils.

Antibody diversity

• Mechanism of antibody diversity: Includes somatic recombination including meiosis in gametes, hypermutation from errors, and gene rearrangement based on antigen.

Immunology Techniques

• In vitro antigen-antibody reactions: Used in serology to study interactions in vitro. These include using techniques that quantify lowest amount of antigen using precipitation which involve soluble antibodies reacting with the antigen to form an insoluble complex. There are various types of precipitation techniques and tests like agar gel immunodiffusion that examine antigen or antibody solutions/complexes.
• Hybridoma technique: Production of monoclonal antibodies in labs/in vitro.

Antimicrobial Agents

• Physical Control: Heat, radiation, and filtration.
• Chemical Control: Targets DNA gyrase, cell wall synthesis, folic acid metabolism, lipid biosynthesis, RNA polymerase, and protein synthesis.

Types of Immunity

• Natural Active Immunity: Acquired during an infection.
• Natural Passive Immunity: Antibody transfer.
• Artificial Active Immunity: Immunization; exposure to a controlled antigen dose.
• Artificial Passive Immunity: Antiserum injection.

Vaccines

• Types of vaccines:
  • Live Attenuated: Weakened pathogen.
  • Killed/Inactivated: Dead pathogen.
  • Subunit: Specific pathogen parts.
  • DNA vaccine: Cloned subunit protein genes.
  • Live Vector: Harmless virus transferring subunit pathogen gene.
  • Recombinant Subunit: Genetically engineered subunits.
  • Conjugated: Combines polysaccharide antigen from pathogen with a protein carrier

Test your knowledge on antibodies, agglutination tests, and related immunological concepts with this comprehensive quiz. Dive into topics such as blood types, monoclonal antibodies, and the functions of complement proteins. Challenge yourself and enhance your understanding of immunology.