Innate immunity Flashcards
What are PRRss (+ example)
Proteins capable of recognizing molecules frequently found in pathogens (Pathogen-Associated Molecular Patterns)
e.g. Toll-Like Receptors - binds PAMPs –> activation results in cytokine expression –> cytokines activate immune cells & increase antivirial immunity
What cells do haematopoietic stem cells give rise to?
Myeloid-lineage cells
Lymphoid-lineage cells
Immune response - What are the lines of defence?
- Physical barriers
* Surface barriers - skin, mucosal membranes
* Epithelial cells - mechanical, selectively permeable barrier - Innate immunity
- Adaptive immunity
What are phagocytes (+ examples)
Any cell capable of ingesting a foreign particle
* granulocytes (mainly neutrophils)
* Macrophages
* Immature dendritic cells
Neutrophils - Function & Characteristics
Function - Phagocytosis & activation of bactericidal mechanisms
* Rapidly invade site of infection
* Ingest bacteria
* Produce antimicrobial products incl. ROI & RNI
* activated neutrophils produce neutrophil extracellular traps (NETs)
Characteristics -
* are granulocytes - contain lysosomal granules
* constitute 30-70% of leukocytes in peripheral blood
* lots produced daily, but short-lived
Macrophage - Function & Characteristics
Function -
* Phagocytosis & activation of bactericidal mechanisms
* Antigen presentation
Characteristics -
* highly phagocytic & contain hydrolytic enzymes
* constitute 3-7% of leukocytes in peripheral blood
* Released as monocytes –> emigrate to tissues –> mature into macrophages
Dendritic cells - Function
Function -
* antigen uptake in peripheral sites
* Antigen presentation
* Bridge between innate & adaptive immune system
Types of granulocytes
Neutrophils
Basophils
Eosinophils
What is opsonisation?
‘Tagging’ pathogens for phagocytosis
* Opsonins (e.g. complement proteins, antibodies) form a surface film on the microbe which facilitates microbe recognition & binding by phagocytes
Basophils - Function + Characteristics
Function -
* promotion of allergic responses & augmentation of anti-parasitic immunity
Characteristics -
* contain large granules containing histamine, heparin, proteolytic enzymes
* least common granulocyte –> 0.1-0.3% of leukocytes in peripheral blood
* Last 1-2 days
Diseases/Conditions associated with high vs low basophil levels
High basophil levels:
* Allergic reactions - basophils release histamine (causes typical allergy symptoms)
* Chickenpox
Low basophil levels:
* cancer -
* Acute infection
Eosinophils - Function + Characteristics
Function - killing antibody-coated parasites
Characteristics -
* constitute 1-5% of leukocytes in peripheral blood
* important role in parasite infections, allergy & asthma
What is eosinophilia (+ causes & e.g.)
Eosinophilia - high eosinophil count
* occurs when either eosinophils are recruited to a specific site, or when the bone marrow produces too many
Caused by: many more
- parasitic & fungal diseases
- alleegic reactions
- skin disorders
Examples:
- asthma
- ezcema
Do antimicrobial peptides (AMPs) preferentially interact with host or bacterial membranes? why?
Bacterial membranes - because of strong (high-affinity) electrostatic interactions between (+)-charged AMP and (-)-charged phospholipids.
When do pathways on the complement cascade converge?
formation of C3 convertase
