MLS 17: Immunology and Serology

MODULE PACKETS IN MLS 17: IMMUNOLOGY AND SEROLOGY

About the Authors

• Jonnalene L.Catigan, RMT: Registered Medical Technologist and lecturer for MLS-17
• Emet Anthony Q.Villafania, RMT: Registered Medical Technologist and lecturer for MLS-17
• Yvonne Mae C.Capatayan, RMT: Registered Medical Technologist and lecturer for MLS-17
• John Robert D.Fundal, RMT: Registered Medical Technologist and lecturer for MLS-17

Overview of Immunology and Serology

• Immunology is the study of the molecules, cells, organs, and systems responsible for the recognition and disposal of foreign material
• Immunology consists of the desirable and undesirable consequences of immune interactions
• Immunology involves the manipulation of the immune system to protect against or treat disease

History of Immunology

• The concept of immunity dates back to ancient Greece in the 5th century BC
• The earliest recognized attempt to intentionally induce immunity was in the 10th century in China
• Lady Mary Wortley Montague introduced variolation to England in the 18th century
• Edward Jenner developed the smallpox vaccine in 1798
• Louis Pasteur developed the first viable vaccine for anthrax and rabies

Significant Milestones in Immunology

• 1798: Edward Jenner develops smallpox vaccination
• 1880-1881: Louis Pasteur develops live, attenuated chicken cholera and anthrax vaccines
• 1883-1905: Elie Metchnikoff discovers phagocytosis
• 1885: Louis Pasteur reports the first therapeutic vaccination for rabies
• 1890: Emil von Behring and Shibasaburo Kitasato propose the humoral theory of immunity
• 1891: Robert Koch demonstrates cutaneous hypersensitivity
• 1894: Jules Bordet discovers complement

Definitions of Terms

• Accelerated rejection: a form of graft rejection that occurs within 1-5 days after second exposure to tissue antigens
• Acquired immunodeficiency syndrome (AIDS): a disease affecting the immune system caused by HIV
• Active immunity: immunity resulting from natural exposure to an infectious agent or administration of a vaccine
• Acute graft-versus-host disease (GVHD): a type of graft-versus-host disease that occurs shortly after transplantation
• Adaptive immunity: a type of resistance that is characterized by specificity for each individual pathogen and the ability to remember prior exposure

Note: These notes only cover the beginning sections of the text, please let me know if you would like me to continue with the rest of the text.### Antigen-Dependent and Independent Phase of B-Cell Development

• Antigen-dependent phase: Final phase of B-cell development, where B cells are stimulated by an antigen and undergo transformation to a blast stage, resulting in the formation of memory cells and antibody-secreting plasma cells.
• Antigen-independent phase: First phase of B-cell development in the bone marrow, resulting in mature B cells that have not yet been exposed to antigen.

Antigen Presentation and Immune Responses

• Antigen presentation: Process by which degraded peptides within cells are transported to the plasma membrane with MHC molecules, allowing T cells to recognize them.
• Antitoxin: Antibody used in passive immunization to neutralize a bacterial toxin.
• Apoptosis: Programmed cell death.

Allergy and Hypersensitivity

• Atopy: Inherited tendency to respond to naturally occurring allergens, resulting in the continual production of IgE.
• Arthus reaction: Type III hypersensitivity skin reaction that occurs when an animal has a large amount of circulating antibody and is exposed to the antigen intradermally, resulting in localized deposition of immune complexes.

Autoimmune Responses

• Autoantibody: Antibody produced against an antigen found on an individual's own cells, tissues, or organs.
• Autoantigen: Antigen that belongs to the host and is not capable of eliciting an immune response under normal circumstances.
• Autoimmune disease: Condition in which damage to body organs results from the presence of autoantibodies or autoreactive cells.

Immune Cells and Responses

• Basophil: Type of white blood cell found in peripheral blood, containing granules that release substances involved in allergic reactions.
• Chemokines: Large family of homologous cytokines that promote migration of white blood cells through chemotaxis.
• Cytokine: Chemical messenger produced by stimulated cells that affects the function or activity of other cells.

Complement System

• Complement: Series of proteins that mediate inflammation and destruction of foreign cells.
• Complement-dependent cytotoxicity (CDC): Killing of cells that results from attachment of antibody with activation of complement.
• Decay-accelerating factor (DAF): Glycoprotein found on peripheral red blood cells, endothelial cells, fibroblasts, and epithelial cell surfaces that dissociates C3 convertases formed by both the classical and alternative pathways of complement.

Immune Assays and Techniques

• Enzyme-linked immunosorbent assay (ELISA): Immunoassay that employs an enzyme label on one of the reactants.
• Fluorescence in situ hybridization (FISH): Technique used to identify a specific region of DNA in a chromosome through binding of fluorescent-tagged complementary DNA probes.
• Fluorescent antinuclear antibody (FANA) testing: Testing to identify the presence of antibody to nuclear antigens, using animal cells and a fluorescent-labeled anti-human immunoglobulin.

Graft Rejection and Immune Tolerance

• Graft-versus-host disease (GVHD): Condition that results from transplantation of immunocompetent cells into an immunodeficient host.
• HLA matching: Pairing up of donor and recipient in a transplant on the basis of similar HLA antigens.
• HLA typing: Laboratory testing used to identify the HLA antigens or genes in a transplant candidate or donor.

Immunoglobulins and Immune Responses

• Immunoglobulin (Ig): Glycoproteins in the serum portion of the blood that are part of humoral immunity.
• Isotype: Unique amino acid sequence common to all immunoglobulin molecules of a given class in a given species.
• Kappa (κ) and lambda (λ) chains: Two types of immunoglobulin light chains.### Immunity and Immune System
• The immune system is responsible for recognizing self from nonself and defending the body against nonself.
• The immune system faces challenges to generate effective protective responses against infectious pathogens.

Body Defenses

• The first line of defense is unbroken skin and mucosal membrane surfaces.
• Physical barriers to infection:
  • Skin
  • Mucosal membrane surfaces
  • Secretions:
    • Mucus (traps microorganisms)
    • Sebum (antimicrobial properties)
    • Lactic acid (antimicrobial properties)
  • Acidic and alkaline fluids (destroy microorganisms)
• Additional protection:
  • Cilia motion in respiratory tract
  • Lysozyme enzyme (destroys bacterial cell walls)
  • Immunoglobulin A (IgA) antibody (found in tears and saliva)

Second Line of Defense: Natural Immunity

• Natural immunity is the ability to resist infection through normally present body functions.
• Characteristics:
  • Nonadaptive
  • Nonspecific
  • No prior exposure required
  • Response does not change with subsequent exposures
• Factors influencing natural immunity:
  • Nutrition
  • Age
  • Fatigue
  • Stress
  • Genetic determinants

Defense System

External Defense System

• Structural barriers that prevent most infectious agents from entering the body:
  • Unbroken skin
  • Mucosal membrane surfaces
  • Secretions (e.g., lactic acid, fatty acids)

Internal Defense System

• Cells (lymphocytes) and soluble factors (e.g., complement) play essential roles.
• Recognizes molecules unique to infectious organisms.

Third Line of Defense: Adaptive Immunity

• Adaptive immunity is characterized by:
  • Specificity for each pathogen
  • Ability to remember a prior exposure
  • Increased response upon repeated exposure
• Both innate and adaptive immunity are essential for good health and operate in concert.