CMB1003/L19 Innate Defences against Infection Flashcards
Give 3 elements of the innate immune response.
Barriers
Cellular defences
Molecular defence (humoral factors)
Give 3 examples of physical and chemical barriers to infection.
Skin
Mucus membranes
Lysozymes in tears
Acid in stomach
Give 3 examples of antibacterial enzymes.
Lysozyme
Secretory phospholipase A2
Tears, saliva, phagocytes
What is the role of PRRs (pattern recognition receptors)?
Allow identification of pathogens
Describe toll-like receptors. (2)
10 in humans
Each has own repertoire of pathogen-associated molecular patterns (PAMPs)
What is a NOD-like receptor? (2)
Intracellular
Nucleotide-binding oligomerisation domain
Give the 3 types of PRR.
Toll-like receptors
NOD-like receptors
RIG-I-like helicases
What kind of molecules can PAMPs be? (4)
Mannose-ruch oligosaccharides
Peptidoglycans
Lipopolysaccharides
Unmethylated CpG DNA
What are leucocytes produced from?
Pluripotent haematopoietic stem cells in bone marrow
Give 3 types of granulocytes.
Neutrophils
Eosinophils
Basophils
Give 3 types of leucocytes.
Lymphocytes
Monocytes
Granulocytes
Tissue mast cells
Give 2 types of cellular defence and their goal.
Phagocytosis
Extracellular killing
Goal - inflammation
What can occur if there is a defect in phagocytes? (3)
Bacterial infections
Fungal infections
Recurrent infections
Describe neutrophils. (3)
Short-lived (<24hr)
Multi-lobed nucleus
Abundant in sites of acute inflammation
Describe mononuclear phagocytes. (3)
Monocytes in blood
Macrophage in tissue
Longer lived cells (months)
Monocyte->macrophage
Give the 5 stages of phagocytosis.
Recognition
Internalisation
Fusion
Killing
Digested products released
Describe oxygen-dependent killing. (2)
Reactive oxygen intermediates bacteriostatic or bactericidal
H2O2 + myeloperoxidase + halid -> halogenation and killing
Give 3 additional functions of macrophages.
Can be activated by bacterial products or cytokines
Secrete soluble factors (cytokines)
Present antigen to lymphocytes
What is extracellular killing effective against? (2)
Organisms too large for phagocytosis
Infected cells
Give 2 cells involved in extracellular killing.
Eosinophils
Natural killer cells
What is the function of eosinophils?
Killing of antibody-coated parasites
What is the function of natural killer cells? (2)
Active against viral infected cells
Attack some tumour cells
What are NK cells activated by? (3)
IFNa
IFNb (type 1)
IL12
What is the function of NK cells? (2)
Produce IFNy
Contain viral infections whilst adaptive/specific response kicks in
What is the function of cytokines?
Stimulate or inhibit activity, proliferation or differentiations of other cells
Give 3 groups of cytokines.
Interferons
Lymphokines
Interleukins
Chemokines
How might a helminth be killed?
Eosinophils secrete chemicals to destroy them
