Innate Immunity Flashcards
What are the characteristics of innate immunity?
Fast, lack specificity, lack memory, no change in intensity = factors that prevent entry, limit growth, contain and clear infect
What are the characteristics of adaptive immunity?
Slow, specific, memory, changes in intensity
What needs to be activated for the adaptive immune response to take place?
Innate immunity
What are the 4 types of barriers in innate immunity?
1) Physical barriers = skin, mucous mem, cilia.
2) Physiological barriers = vomiting, diarrhoea, coughing, sneezing.
3) Chemical barriers = low pH, antimicrobial molecules (IgA, lysozymes, mucus).
4) Biological barriers = normal flora.
How can normal flora be displaced to a sterile location?
Breaking the skin barrier, faecal-oral route, faecal-perineal-urethral route, poor dental hygiene/dental work
Other than displacement how can an infection take place?
Immune-compromised host, normal flora depleted by Abx
Innate barriers being the first line of defence in innate immunity, what is the second?
Phagocytes, complement, cytokines = inflam
What is the role of a macrophage?
Phagocyte, prod chemokines/cytokines, APC
What is the role of a neutrophil?
60% of WBCs, increase in infect, recruited by chemokines, phagocytise pyogenic bacteria
What is the role of a basophil?
Contain heparin and histamine = inflam, allergic reactions
What is the role of an eosinophil?
Parasites
What is the role of a NK cell?
Kill abnormal host cells
What enables a phagocyte to recognise a microbe?
PAMPs (pathogen associated molecular patterns) on the microbe are recognised by PRRs (pathogen recognition receptors / toll like receptors) on the phagocyte AND/OR opsonisation
Name some opsonins
Complement = C3b, Ab = IgG IgM, acute phase proteins = CRP
What is the diff between a phagosome and a phagolysosome?
Phagosome = phagocytic vesicle. Phagolysosome = phagocytic vesicle fused with lysosome
Outline a phagocytes intracellular killing mechanism
O2 dependent = hydrogen peroxide, hydroxyl radical, nitric oxide, oxygen radical, hypohalite.
O2-independent = lysosome, lactoferrin/transferrin
What are the antimicrobial actions of the complement system?
1) C3a C5a = recruitment of phagocytes.
2) C3b-C4b = opsonisation.
3) C5-C9 = killing, MAC
TNFα/IL-1/IL-6 from macrophages, has what actions?
Liver prod CRP, bone marrow cause neutrophil mobilization, vasodilation, increased vascular permeability, hypothalamus increases temp
What reasons would cause decreased phagocytosis?
Decreased spleen function, decreased neutrophil count, decreased neutrophil function
Why does losing the spleen put you at an increased risk of severe infection?
When the spleen is no longer present (asplenia), IgG and C3b are still bound to bacteria, but they cannot be removed from the blood circulation due to the loss of the splenic macrophages.
