Pulmonary defense Flashcards
(27 cards)
What are the Upper respiratory host defenses?
– Anatomic barriers (epiglottis)
– Frequent branching of pulmonary tree • Aerodynamic filtration of inspired air
– Mucociliary clearance of particulates
– Cough Response
what are lower respiratory tract defenses?
– Phospholipid surfactant
– Proteins (immunoglobulins, complement)
– Cellular defenses • Lymphocytes • Alveolar macrophages • Polymorphonuclear neutrophiles
Explain the lung host defenses in the nasopharynx? What are the defects? What are the potential infection problems?
- Ciliated and squamous epithelium – Filtering system removes particles 10 mm or larger – Mucous layer with IgA, IgG to prevent epithelial attachment of bacteria
- Defects – Poor nutrition
- Potential infection problems
– Colonization with pathogenic GNB, Normal colonization is 2-6%, 4 days in ICU (40%), Colonization to infection (23%)
Conducting Airways defenses?
- Mechanical barriers (larynx) and airway angulation
- Bronchoconstriction
- Mucociliary transport mechanisms – Tracheobronchial secretions – Cilia
- Local immunoglobulin coating – Secretory IgA major immunoglobulin upper airways – Prevent adherence and absorption – Antibody activity against viruses, bacteria, allergens
Explain the defects and potential infection problems with Mechanical barriers in the conducting airways?
- Mechanical barriers (larynx) and airway angulation
- Defects – Endotrachael tube – Tracheostomy
- Potential infection problem – Aspiration • Direct entry of microorganisms into distal airway
Explain the defects and potential infection problems with Bronchoconstriction?
- Bronchoconstriction
- Defects – Hyperactive airways – Intrinsic asthma
- Potential infection problem – Poor removal of secretions – Excessive thick secretions – Secondary infection
Explain the defects and potential infections with Mucociliary transport mechanisms?
- Mucociliary transport mechanisms – Tracheobronchial secretions – Cilia
- Defects – Cilia toxic • Viruses, mycoplasma pneumonia – Intrinsic cilia defects • Chronic inflammation (smoking) • Kartagener syndrome
– Potential infection problem • Stagnant secretions • Bronchitis, bronchiectasis, sinusitis • Cystic fibrosis – Ciliatoxic factor secretions – Tenacious secretions – Infection (mucoid form pseudomonas)
Explain the defects and potential infections with local immunoglobulin coating in the conducting airways?
- Local immunoglobulin coating – Secretory IgA major immunoglobulin upper airways – Prevent adherence and absorption – Antibody activity against viruses, bacteria, allergens
- Defects – IgA deficiency – Functional deficiency by bacterial breakdown (protease) • Sreptococcus pneumoniae, haemophilus influenza
- Potential infection problem – Sinopulmonary infection – Abnormal colonization with certain bacteria
What are the special host defense mechanisms in the lungs?
1) . Surfactant
2) . • Antibody-Mediated Immunity
3) . • Immunoglobulins
4) . Complement
5) . Alveolar Machrophage
What is surfactant secreted by what does it do? Potential defect? Potential infections problem?
Surfactant
– Secreted by type II pneumocytes – Antibacterial activity • Staph and GNB
– Potential defect • Decreased synthesis • Acute lung injury
– Potential infections problem • Loss of opsonization activity • Alveolar collapse (atelectasis)
Explain uptake of antigen in the respiratory tract: conducting airways?
Conducting Airways
– Local defenses
– Mucosal defenses:
• Immunoglobulins • Local phagocytes • Into systemic circulation (blood, lymphatics) – Regional lymph nodes – RES system
– Peripheral Parenchyma (Alveoli) • Engulfed and processed by alveolar macrophages – Sent to T lymphocytes » Lymphokine production (enhance PMN, macrophages) » Direct cellular cytotoxicity
Explain antibody mediated immunity specific mechanisms?
Antibody-Mediated Immunity
– Depends on B lymphocytes
– Recruits acute inflammatory cells
– Enhances phagocytosis
– Augments microbicidal activity
– Neutralizes toxins
– Inhibits microbial growth and adherence
– Activates complement cascade
Explain the immunoglobulins in the lung?
– IgA • Neutralize reparatory viruses, exotoxins • Agglutinate microbial organism for mucociliary escalator • Prevent bacterial attachment to epithelial cells
– IgG and IgM • Most effective opsonizer (IgG) • Agglutinators of particulate antigens • Initiate complement cascade • Neutralize or lyse bacteria, viruses
– IgE • Host resistance to parasitic, viral infection
Explain the complement in the lungs? potential defects? Potential infection problems?
Complement – Properdin Factor B • Direct lysis • Opsonization
– Defects •C 3 and C5 deficiency
– Potential infectious problem • Non life-threatening infection
Explain the primary and secondary defenses of the alveolar macrophage?
- Primary Defense – Phagocytic against various antigens
- Secondary Defense
– Modulation of function of other inflammatory and immune responses • Presentation of processed antigen to T lymphocytes • Complement fragments • Chemotactic factors to PMN • Lymphocyte chemotaxin • Leukotrienes
List intracellular bacteria that are contained in macrophages?
– Mycobacterium tuberculosis
– Mycobacterium lepraemurium
– Toxoplasma gondii
– Leishmania donovani
– Legionella pneumophilia
– Pneumocystis jiroveci
– Listeria monocytogenes
– Cytomegalovirus
– HIV
List the role of the cell mediated immunity in the lungs?
Cell-Mediated Immunity – Depends on T lymphocytes – Recruits chronic inflammatory cells – Effects cytolysis of virally infected cells – Activates macrophages for enhanced intracellular killing – Induces granuloma formation
What are the two major mechanisms of T cell functional activity?
– Two major mechanisms of T cell functional activity
- Lymphokine-mediated reactions
- Cell-mediated cytotoxicity – Cytolytic T effector cells (Neoplastic cells, viral infected cells) – Natural killer lymphocytes – Antibody-dependent cellular cytotoxicity (Macrophages binding to antibody-coated cells)
What cytokines have a role in lung innate immunity?
– TNF-alpha
– IL 10, IL-12
– Chemokines
– Interferon-gamma
– G-CS
expalin the role of IL-12 cytokines in the lung innate immune system?
IL-12
– Enhances CMI to intracellular pathogens
– Produced by AM, pulmonary epithelial cells, PMN
– Increased levels resulted in bacterial killing and improved survival
Explain the role of TNF-alpha in the lung innate immune system?
TNF alpha
– LPS potent stimulus of TNF alpha
– TNF- stimulates AM to produce IFN -gamma to stimulate more cytokines
– Increase local levels in lung reduce bacterial counts and increase survival
– Increase systemically may worsen survival
Role of IL-10 in the lung innate immune system?
IL 10
– Anti-inflammatory cytokine
– Down regulates production of TNF- , IFN-gamma, and chemokines
– Allows proliferation of bacteria
Role of G-CSF?
G-CSF
– Maintain increase neutrophile delivery
– Increase neutrophile function
– Enhance clearance of bacteria and virulence faction
– Non-neutrophile mediated effects
– Antibiotic interactions • Increase levels of certain antibiotics into neutrophiles
Explain Polymorphonuclear cells in the lung?
• Most numerous and important defense once fullblown inflammatory response occurs
– Sequestered in interstitial areas and capillaries
– Adherence to endothelium
– Chemotactic attraction to inflamed site
– Diapedesis into tissue
– Ingestion and destruction of microbes
