Early Immune Responses Flashcards
Innate immunity
initial nonpathogen specific protection against infection
Pathogen
a microorganism that is able to breach host barriers to gain access to a tissue site where it can replicate and or establusth a latent infection
Extracellular pathogens
replicate within the extracellular spaces of tissues
Intracellular pathogens
replicate within the host cells
Viruses
intracellular bacterial pathogens
Innate vs adaptive immunity
similarities and differences
Similarities: recognition, activation, and effector phases
Differences: response time and specificity
Routes if infection
Wounds and abrasions
Insect bites
Airway
GI
Reproductive tract
Cetegories of natural barriers
Mechanical
Chemical
Microbiological
Host pathogen balance
The most successful pathogens are able to breech all 3 barriers
A defect in onne, two, or all three host barriers increases the susceptibility to infection
To clear extracellular pathogens (eg bacteria like e coli) from blood, mucosal surfaces, and tissues, innate immunity relies primarily on…
Epithelial defenses
Recruitment of phagocutes (neutrophils, macrophages) from blood
Opsonization for uptake and killing by phagocytes
To clear viral pathogens from infected cells, innate immunity relies primarily on…
Activation of type 1 interferon
Activation of NK cells to lyse the pathogen infected cell
Epithelial barriers
Mucus
Epithelial tight junctions
Antimicrobial peptides
- Defensins
- Cathelicidins
- Lysozyme
Defensins
Antimicrobial peptides (30 aas) directly damage pathogen membranes by inserting in them, creating a pore that leads to loss of osmotic balance
Vaginal tract commensal bacteria
secretes enzymes that keep low pH and inhibit pathogen growth
Innate cell defense: phagocytes
macrophages
neutrophils
dendritic cells
Macrophages
long lived
present in blood and tissues
