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Questions and Answers
What is a key requirement for an antigen to be considered immunogenic?
What is a key requirement for an antigen to be considered immunogenic?
What is the role of macrophages in the immune response?
What is the role of macrophages in the immune response?
Which of the following best describes chronic inflammatory diseases?
Which of the following best describes chronic inflammatory diseases?
In the context of immune cell activities, what occurs during lymphocyte recirculation?
In the context of immune cell activities, what occurs during lymphocyte recirculation?
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Hypersensitivity diseases are primarily characterized by what?
Hypersensitivity diseases are primarily characterized by what?
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What is the primary significance of co-dominant expression of MHC proteins in humans?
What is the primary significance of co-dominant expression of MHC proteins in humans?
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What percentage of HLA identity is shared between siblings?
What percentage of HLA identity is shared between siblings?
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How do HLA-haplotypes behave during inheritance?
How do HLA-haplotypes behave during inheritance?
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Which statement best describes the role of HLA class I genes in the immune system?
Which statement best describes the role of HLA class I genes in the immune system?
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How can HLA genes influence disease susceptibility?
How can HLA genes influence disease susceptibility?
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What is the impact of insufficient dosage on immunogens?
What is the impact of insufficient dosage on immunogens?
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Which class of antibody is primarily responsible for mediating Type I hypersensitivity reactions?
Which class of antibody is primarily responsible for mediating Type I hypersensitivity reactions?
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Which statement about the immunogenicity of nucleic acids is true?
Which statement about the immunogenicity of nucleic acids is true?
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What is a key characteristic of proteins and glycoproteins related to immunogenicity?
What is a key characteristic of proteins and glycoproteins related to immunogenicity?
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Cross-reactivity of antibodies typically applies to what type of antigens?
Cross-reactivity of antibodies typically applies to what type of antigens?
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What is the primary function of IgM in the immune response?
What is the primary function of IgM in the immune response?
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Which immunoglobulin is predominantly found in mucosal and respiratory secretions?
Which immunoglobulin is predominantly found in mucosal and respiratory secretions?
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What does the placental passage of antibodies primarily refer to?
What does the placental passage of antibodies primarily refer to?
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What is a consequence of antigen stability in the context of immune response?
What is a consequence of antigen stability in the context of immune response?
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Which immunoglobulin class is most effective for complement fixation?
Which immunoglobulin class is most effective for complement fixation?
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Which property is essential for a substance to be recognized as an immunogen?
Which property is essential for a substance to be recognized as an immunogen?
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Which size range is typically associated with a substance being considered immunogenic?
Which size range is typically associated with a substance being considered immunogenic?
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What characteristic of an antigen affects its immunogenicity regarding chemical complexity?
What characteristic of an antigen affects its immunogenicity regarding chemical complexity?
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In the context of immune responses, what is the primary function of lymphatic vessels?
In the context of immune responses, what is the primary function of lymphatic vessels?
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Which of the following best describes the relationship between antigen size and immunogenicity?
Which of the following best describes the relationship between antigen size and immunogenicity?
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What is the significance of co-dominant expression of MHC proteins in human genetics?
What is the significance of co-dominant expression of MHC proteins in human genetics?
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What is the expected chance of two unrelated individuals sharing HLA identity?
What is the expected chance of two unrelated individuals sharing HLA identity?
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If both parents have the same allele at one locus, what is the expected HLA type expression for the child?
If both parents have the same allele at one locus, what is the expected HLA type expression for the child?
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What role do HLA class I genes play in immune response?
What role do HLA class I genes play in immune response?
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What does the HLA haplotype inheritance model suggest about the transmission of HLA genes?
What does the HLA haplotype inheritance model suggest about the transmission of HLA genes?
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Which function is NOT associated with IgG antibodies?
Which function is NOT associated with IgG antibodies?
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Which of the following is a characteristic unique to IgA?
Which of the following is a characteristic unique to IgA?
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Which immunoglobulin class is primarily involved in mediating hypersensitivity reactions?
Which immunoglobulin class is primarily involved in mediating hypersensitivity reactions?
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What is one of the primary functions of IgM in the immune response?
What is one of the primary functions of IgM in the immune response?
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Which of the following statements about IgG is false?
Which of the following statements about IgG is false?
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Which characteristic distinguishes the four subclasses of IgG?
Which characteristic distinguishes the four subclasses of IgG?
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Which immunoglobulin is primarily responsible for the first line of defense against bacterial infections in mucosal tissues?
Which immunoglobulin is primarily responsible for the first line of defense against bacterial infections in mucosal tissues?
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Which immunoglobulin class is best known for its role in immediate hypersensitivity and allergic reactions?
Which immunoglobulin class is best known for its role in immediate hypersensitivity and allergic reactions?
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Which statement regarding IgA activity is true?
Which statement regarding IgA activity is true?
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In terms of immunoglobulin production, which class is primarily associated with the body's immediate response to infection?
In terms of immunoglobulin production, which class is primarily associated with the body's immediate response to infection?
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Study Notes
Cardinal Signs of Inflammation
- Rubor - redness
- Tumor - swelling
- Calor - heat
- Dolor - pain
- Loss of function (functio laesa)
Leukocyte Adherence to Endothelium
- Blood flow slows
- Wall shear stress decreases
- Peripheral leukocyte positioning
- Margination (neutrophils adhering and aligning to vessels)
- Rolling (cells bind and detach)
- Adhesion molecules (cells adhere via these molecules)
Chemotaxis
- Leukocytes cross endothelium & basement membrane
- Extravascular tissue entry
- Chemotactic gradient followed by cells
Chemotaxis: Continued
- Chemotaxis defined as leukocyte movement to tissue injury
- Bacterial products (e.g., cytokines) are chemotactic
- Leukocyte type depends on stimulus and response timing
- Acute inflammation dominated by neutrophils
Contrast in Inflammation
- Viral infections - lymphocytes first
- Hypersensitivity reactions - lymphocytes & plasma cells
- Allergic reactions - eosinophils dominant
Bacterial vs. Viral Pneumonia
- Bacterial pneumonia - caused by Streptococcus pneumonia
- Immune cells: neutrophils & macrophages
- Viral pneumonia - caused by SARS-CoV-2
- Immune cells: lymphocytes
- Bacteria enter alveoli/begin to grow, capillaries open/ neutrophils combat bacteria, macrophages clear debris.
- Virus multiplies in cells, destroys cells; lymphocytes destroy virus-infected cells/type 2 pneumocytes.
Eosinophils
- White blood cell part of innate immune system
- Protect from allergens and infections (e.g., parasites)
- In response to allergies, hives, parasites, autoimmune responses, medications, etc.
Acute Inflammation: Morphologic Patterns
- Serous inflammation
- Fibrinous inflammation
- Suppurative inflammation
- Abscesses
- Ulcers
Serous Inflammation
- Cell poor fluid in tissues
- Early stage of acute inflammation
- Skin burn results in blisters and serous fluid accumulation
Fibrinous Inflammation
- Increased vascular permeability allows larger molecules to seep
- Fibrinous exudates form when vascular leaks are significant
- Examples: meningitis and pericarditis
- Fibrinous exudates are usually cleared by macrophages
- If not removed, stimulates fibroblasts and blood vessels leading to scarring (organization)
- Example: Fibrinous pericarditis
Purulent Inflammation
- Characterized by pus (neutrophils, necrotic debris, and fluid)
- Same as suppurative inflammation
- Common cause: bacteria
- Example: acute appendicitis
Abscesses
- Localized collections of purulent inflammatory tissue confined to a space
- Central portion is necrosis
- Periphery: zone of preserved neutrophils and fibroblasts
Ulcers
- Local defects on tissue/organ surfaces, due to inflamed necrotic tissue sloughing
- Tissue necrosis is involved
- Example: peptic ulcer disease
Chronic Inflammation Morphologic Features
- Mononuclear cells (macrophages, lymphocytes, plasma cells) dominate
- Lymphocytes (T cells), for example, secrete interferon to activate macrophages
- Interferon gamma is a cytokine (mediator of inflammation) causing tissue destruction
- Healing via fibrosis
Mast Cells
- Involved in insect bites, medication/drug reactions, and allergies
Cellular Adaptation: Hyperplasia and Hypertrophy
- Cells respond to increased demand by proliferation or enlargement (or both)
- Hyperplasia involves cellular proliferation
- Hypertrophy involves cellular enlargement
- Metaplasia is another type of adaptation
Metaplasia Examples
- Columnar to squamous epithelium (bronchial epithelium, in response to toxins, such as cigarette smoking)
- Squamous to columnar epithelium (esophageal epithelium, in response to repeated exposure to acidic gastric contents)
- Biliary tree epithelium in response to stones
Cell Injury Manifestations: Intracellular Accumulations
- These accumulating substances can be normal, abnormal, endogenous, or exogenous
Reversible Cell Injury Microscopic Changes
- Cellular swelling (cytoplasm)
- Fatty change
Irreversible Cell Injury Underlying Processes
- Hypoxia (a common underlying process)
Types of Necrosis
- Coagulative necrosis
- Liquefactive necrosis
- Caseous necrosis
- Fat necrosis
- Fibrinoid necrosis
Patterns of Tissue Necrosis
- Large numbers of cells undergoing necrosis = necrotic tissue or organ
- Distinct patterns exist, giving clues about the underlying cause
Coagulative Necrosis
- Tissue architecture preserved initially
- Protein denaturation, enzymatic changes occur
- Eosinophilic, anucleate cells may persist
- Example: myocardial infarction (localized area of coagulative necrosis)
Liquefactive Necrosis
- Digestion of dead cells resulting in liquid, viscous mass forming pus
- Common in bacterial/fungal infections
- Example: brain tissue ischemia
Gangrenous Necrosis
- Coagulative necrosis in limbs or bowels
- With infection, turns into liquefactive necrosis ("wet" gangrene)
- Dry (coagulative) gangrene is a type of gangrene
Caseous Necrosis
- Friable, white cheese-like appearance
- Necrosis with inflammatory foci (granulomas)
- Often encountered in tuberculosis
Fat Necrosis
- Focal areas of fat destruction
- Common in inflamed pancreas/trauma to breast
Fat Necrosis with Dystrophic Calcification
- Fat necrosis resulting in calcification
Fibrinoid Necrosis
- Immunological reactions in blood vessels
- Fibrin deposition is a feature
Two Types of Immunity
- Innate (non-specific): basic elements, readily available
- Acquired (specific): more specialized elements
Hematopoiesis
- Development of blood & derived cells in bone marrow, lymph nodes, tissues
- Lymphoid lineage: lymphocytes (B cells, T cells, NK cells)
- Myeloid lineage: granulocytes, macrophages, erythrocytes, megakaryocytes
Antigen-Presenting Cells (APCs)
- Dendritic cells, macrophages, B lymphocytes
- Take up and digest antigens (pathogens or foreign proteins)
- Digested fragments displayed on MHC class II molecules
- Presentation to CD4+ T cells (e.g., causing antibody production)
Lymphocyte Recirculation
- Immune cells searching for pathogens via lymph, blood, & lymphatic vessels
- Cells pick up exogenous antigens and bring to the draining lymph node
- Specific immune response follows
The Big Picture (Immune Response)
- Primary response & APC presenting antigen to T cells
- Transitions from innate to adaptive (especially concerning APC's)
Requirements for Immunogenicity
- Foreignness: not self-reacting (exception: autoimmune diseases); more foreign = more immunogenic
- Size: > 6 kDa generally immunogenic; < 1 kDa not
- Chemical complexity: homopolymers of amino acids are not immunogenic
- Degradability: susceptibility to enzymatic degradation; stability important for antigen presentation
- Dosage: insufficient dosage creates tolerance; repeated administration required for response
Major Classes of Antigens
- Carbohydrates (immunogenic as part of glycoproteins)
- Lipids (rarely immunogenic)
- Nucleic acids (not immunogenic, except in systemic lupus erythematosus)
- Proteins/glycoproteins (very immunogenic)
Cross-reactivity
- Antibodies specific to one antigen can react with a second antigen (especially antigens that are closely related)
- Example: toxins versus toxoids
Five Major Antibody Classes
- IgG, IgA, IgM, IgD, IgE
IgG Subclasses
- Important differences in occurrence, half-life, complement binding, and placental passage
- Vary in their ability to bind monocytes
- Key feature: placental passage
IgG: Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)
- IgG-mediated activation of complement
- Toxin/viral neutralization
- Bacterial immobilization
Antibody Levels Early in Life
- IgM first to rise from fetus
- IgG rises (passively transferred/maternal)
- IgA rises later
IgM
- First antibody produced in response to infection/immunization
- Efficient in complement fixation
IgA
- Primarily found in secretions (tears, saliva, etc.)
- Important part of respiratory and mucosal surfaces' first line defense
- Antibacterial/antiviral activities
IgE
- Mediates Type I hypersensitivity reactions
- High levels during parasitic infections
HLA Genes and Inheritance
- MHC genes inherited from both parents as a haplotype
- Individuals expressing particular combinations of HLA genes may have greater disease susceptibility/resistance
- The inheritance of genes in combination determines the outcome for particular diseases
HLA Class I & II Expression
- HLA genes expressed in professional APCs (dendritic cells, macrophages, B cells)
- HLA class II expression can be induced by cytokines (e.g., interferon gamma)
MHC Class I Antigen Processing Pathway
- Endogenous antigens (e.g., viral proteins) are processed and presented to CD8+ T cells
MHC Class II Exogenous Antigen Processing Pathway
- Exogenous proteins taken into the cell, degraded into peptides
- Peptides presented to CD4+ T cells
Cross-Presentation
- Dendritic cells carry exogenous antigens to MHC I, activating cytotoxic T cells from extracellular sources
Chronic Inflammation Cells
- Lymphocytes (microbes/environmental antigens activate and propagate inflammation)
- Macrophages (professional phagocytes, activated by classical/alternative pathways; secrete factors for angiogenesis and fibrosis)
- Eosinophils (granules containing toxic proteins against parasites/epithelial cells)
Granulomatous Inflammation
- Cells (macrophages & lymphocytes) form collections to contain an offending agent
- This inflammation contains central necrosis sometimes
Tuberculosis
- Granulomatous disease caused by mycobacteria infection
General Inflammation Take Aways
- Excessive inflammation can lead to disease & increase infection risk
- Inflammation targets malignant cells for therapeutic interventions
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Description
This quiz covers the critical aspects of inflammation, including the cardinal signs, leukocyte behavior, and chemotaxis mechanisms. You'll explore the differences in immune responses to bacterial and viral infections, as well as the types of leukocytes involved. Test your knowledge on these fundamental concepts in immunology.
