Innate Immunity Flashcards
Three physical barriers in the innate immune system
Skin
Mucous Membrane in the mouth, resp tract, GI tract, Urinary tract
Bronchial cilia
4 Physiological barriers to infection
Diarrhoea
Vomiting
Coughing
Sneezing
2 Chemical barriers? (Note give examples 5)
Low pH (Eg. skin 5.5, stomach, vagina)
Antimicrobial molecules eg. IgA, Lysozyme, Mucus, Β-defensins, gastrci acid and pepsin
What is the main biological barrier to infection? Where is it located?
Normal flora
Nasopharynx, mouth, throat, skin, GI tract, Vagina
Benefits of the normal flora?
Compete with pathogens for attachment sites and resources
Produce antimicrobial chemicals
Synthesise vitamins
4 reasons why someone may be immunocompromised?
Chemo
AIDS
Diabetes
Malignant diseases
3 features of macrophages?
Phagocytosis
Professional antigen presenting cells
Produce cytokines
What are monocytes?
Present in the blood, recruited at the site of infection and differentiate into macrophages
what is a chemokine?
Chemokines are chemicals that are able to induce chemotaxis (Neutrophils move up the chemical gradient to the site of infection)
Function of basophils and mast cells?
Early promoters of inflammation
Important in allergic responses
Function of Eosinophils?
Defence against multi-cellular parasites
Function of Natural killer cells
Kill abnormal host cells
Function of dendritic cells?
Present antigens to T cells. Activate Adaptive immunity
How does the macrophage recognise the bacteria?
Looks for Pathogen associated molecular patterns on the pathogen. These aren’t present on host cells PAMPs
Phagocytes have pathogen recognition receptor to recognise PAMPs (Eg. Toll like receptor)
What is opsonisation?
Coating proteins called opsonins bind to microbial surfaces and leads to enhanced attachment of phagocytes and clearance of microbes
Give 3 types of opsonins
Complement proteins
Antibodies
Actue phase proteins
Describe the process of phagocytosis and degradation of pathogens 6
- Phagocyte chemotaxis to microbe, and adheres to it
- Ingests microbe
- Forms a phagosome
- Lysosome fuses with the phagosome to form a phagolysosome
- Enzymes digest ingested microbes
- Discharge of waste materials
What is the oxygen dependent pathway of killing in phagocytes? What is the oxygen independent pathway of killing?
Respiratory burst
Toxic oxygen products eg.Hydrogen peroxide, hydroxyl radical, Nitric oxide etc..
Lysozyme, lactoferrin or transferrin, cationic proteins, proteolytic and hydrolytic enzymes
What are the two pathways for activating the complement system?
Alternative pathway- Initiated by cell surface microbial constituents (Eg. endotoxins)
MBL pathway (Mannose Binding Lectin)- MBL binds to mannose containing residues of proteins found on many microbes
What are the actions of macrophage derivved TNFa, and interleukins
Organ then action
Liver: Release of opsonins eg. CRP and MBL (–>complement activation)
Bone marrow: Neutrophil mobilisation
Inflammatory actions: Vasodilation, cascular permeability and adhesion molecules–> attraction of neutrophils
Hypothalamus: Increased body temp
What can you start to get problems with infections (Clinical conditions)? 3
Decreased spleen function
Decreased neutrophil number
Decreased neutrophil formation
