Innate Immunity 2 Flashcards
(42 cards)
What cells can carry out phagocytosis?
Neutrophils and Macrophages
What are the innate immune cells?
Neutrophils
Macrophages
Dendritic cells
Natural Killer cells
What do cytokines do to blood vessels?
Dilate them, making them more permeable which allows immune cells to pass through
What is leukocyte extravasation?
The movement of leukocytes out of the circulatory system and towards the site of tissue damage / injury
What are examples of cell adhesion molecules?
ICAM-1 and ICAM-2
Where are cell adhesion molecules located and what do they bind to?
Found on the endothelium and they bind to interns on leukocytes
What are integrins?
Transmembrane proteins that are involved in the adhesion of cells to each other and also to their substrates.
What is phagocytosis?
The capture and digestion of foreign material
What are examples of opsonins?
Complement components (C3b)
Collectins (e.g. MBL)
Antibodies
What are examples of phagocytic receptors?
Complement receptors
Fc receptors
Mannose receptors
Scavenger receptors
What are the steps of receptor mediated phagocytosis?
1) Phagocytic receptor recognises a component of microbial surface and binds to the microorganism
2) Microorganism gets internalised by receptor-mediated endocytosis
3) Fusion of the endoscope with a lysosome forms a phagolysosome and the microorganism gets broken down
What are neutrophil extracellular traps (NETs) and how do they work?
A special form of cell death that some neutrophils can undergo when activated (NETosis)
During this, nuclear chromatin gets released by cells - trapping microorganisms and aiding phagocytosis
What do Pattern Recognition Receptors (PRRs) recognise?
Pathogen-Associated Molecular Patterns (PAMPs)
What are some examples of PRRs?
Toll-like receptors (TLRs)
NOD-like receptors
Rig-I like receptors (RLRs)
Cystosolic DNA sensors (CDS)
What does DAMPs stand for and where are they released from?
Damage-assocaited molecular patterns
Released from necrotic cells
Due to the rapid evolution of microorganisms, what do PAMPs detect?
Highly conserved and essential components of microbes
E.g. cell wall structures and nucleic acids
What are the two sections of Toll-like receptors?
Extracellular side which has LRRs (Leucine-rich repeats) that are the site of pathogen binding
Cytosolic with a TIR-domain which is a conserved stretch of roughly 200 amino acids
How are TLRs able to form heterosexual/homodimers?
TLR-1 and TLR-2 have binding sites for lipid side chains of triacyl lipopeptides.
Binding of each TLR to the same lipopeptide then induces dimerisation.
Where can TLRs be found?
Cell surface and endosome surface
Which TLRs are found on the cell surface and which TLRs are found on the endosome surface?
Cell surface = TLR 1, 2, 4, 5 and 6
Endosomal = TLR 3, 7, 8, 9, 1o
What type of microorganism’s products do TLRs detect?
Cell surface = Bacterial
Endosomal = Viral
How is TLR signalling able to aid host defence?
Induces genes involved in host defence (e.g. chemokines and antimicrobial peptides)
What is Waldenstrom macroglobulinemia?
A rare type of non-Hodgkin lymphoma caused by a MyD88 (protein) gain of function mutation.
B cells make large amounts of IgM which can cause excessive bleeding, vision problems and headaches.
Lymphoma cells proliferating in the bone marrow can cause anaemia, neutropenia and thrombocytopenia.
What are Nod-like receptors?
Cytoplasmic PRR molecules and they are nucleotide-binding leucine rich (NLR)
