Intro to immunology Flashcards
Skin - how does it act as a barrier to infection?
- Physical barrier - tightly packed keratinised cells
- Low pH
- Low oxygen tension
- Sebaceous glands produce hydrophobic oils + lysozymes
Secreted mucous - 4 ways that it acts as a barrier to infection?
- Secretory IgA
- lysozyme
- Lactoferrin (starves bacteria of iron)
- Physical barrier
Commensal bacteria - how doe sit act as a barrier to infection?
- Compete with pathogenic organisms for scarce resources
- Produce fatty acids and bactericides that inhibit pathogen growth
Polymorphonuclear cells inc?
Neutrophils
Eosinophils
Basophils/mast cells
Actions of polymorphonuclear cells
- Migrate rapidly to site of injury
- Secrete cytokines and chemokines
- Express receptors for cytokines + pattern recognition + Fc of Ig
- Phagocytosis + non/oxidative killing
How do macrophages differ from polymorphonuclear cells?
Present processed antigen to T-cels
Cytokines vs chemokine
Cytokines = increase vascular permeability Chemokine = attract phagocytes
2 ways in which microorganisms are recognised by innate immune response?
- Pattern recognition receptors - eg TLRs and mannose receptors
- Fc receptors - for Fc portion of Ig to allow recognition of immune complexes
Which molecules facilitate endocytosis?give 3 egs
Opsonisation
- Antibodies (bind to Fc receptors)
- Complement components
- Acute phase proteins (CRP)
2 killing methods by polymorphonuclear cells?
Oxidative killing - NADPH oxidase complex converts O2 to reactive oxygen species. Myeloperoxidases: production of hydrochlorous acid (an antimicrobial!)
Non-oxidative killing - release of lysozyme/lactoferrin from granules into phagolysosyme
What happens after neutrophils after they phagocytose lots?
Depletes neutrophil glycogen reserves –> neutrophils die –> residual enzymes released –> accumulate –> pus
