Lecture 16 Flashcards
What are the two types of immune responses?
Innate and adaptive
What is the first line of defense of immunity?
Epithelial barriers
Skin
Bronchial
Gut
What are features of the microbiological barrier?
Produce metabolic products to stop pathogen growth
deplete nutrients for pathogens
provide protective layer
Where are immune cells produced?
Bone marrow,
Blood
Lymph nodes
What are the two types of immunometabolism?
systemic immunometabolism
cellular immunometabolism
What are the function of macrophages?
phagocytosis
cytokine production
antigen presentation
What are the functions of dendritic cells?
Antigen uptake
cytokine production
antigen presentation
What are the function of neutrophils
phagocytosis
What is the basic principle of the immune system?
recognise invading microorganisms
formulate a response to clear the infection
What are PAMPs?
Pathogen associated molecular patters: Unique to pathogens and recognised by immune system
What are PRRs (Patterns recognition receptors)?
PRRs recognize PAMPs (evolutionary conserved)
What are the three types of PRRs?
Toll like receptors (TLR)
Nod like receptors (NLR)
Rig like helicases (RLH)
What are TLRs (Toll like receptors)
Transmembrane protein recognize PAMPs thorugh ligand binding domain
What are NLR and RLH?
soluble molecules that scan the cytoplasm for PAMPs
What are TLR recognized by?
TIR domain and Leucine rich repeat (LRR) which recognizes the PAMPs
What is the TLR cascade?
TLR acivates ubiquitine ligase -> activating NfkB and induce cytokine production in the nucleus
What are DAMPs (Danger Associated Molecular
Patterns) and what do they do?
DAMPs are released when cells are dying and can activate PRRs (serve as warning to other cells)
What are cytokines?
peptides that mediate communication between cells
mediate immune response and inflammation
What are chemokines?
Peptides that recruite immune cells to infection or injury
How are pathogens cleared by the immune system?
Phagocytosis (bacteria)
Killing of pathogens (parasites)
killing of host cells (viruses)
How are pathogens cleared by macrophages?
Recptors on mycrophages bind microbes and their components -> internalize them and break them down in phagolysosomes
What are B-cells?
Sole producers of antibodies
How can antibodies recognize several different antigens?
The posses a region of hypervariability for binding to antigens
WHat do T-cells do?
mediate immune protetcion (CD4 and CD8 cells)
recognize antigens by MHC presentation
What do CD8 T-cells do?
Recognize antigens on cell surface and kill the cells. Antigen is presented on MHCI cells
What do CD4 T-cells do?
MHCII antigen presentation -> activate B-cells and macrophages
Why are lymphocytes so special for immune responses?
Each lymphocyte only recognizes 1 antigen and there are millions which results in millions of different specificities
How is it possible to produce millions of different antigen recpetors when the genome only has 20000 genes? (lymphocytes)
Through gene rearrangment (V(D)J recombination)
1 V 1 D and 1 J gene come together and are further augmented by deletions / insertions to generate millions of antigen receptors
How do antigen receptors discriminate between
self and non-self?
self reactive lymphocytes are degraded (clonal deletion) only mature lymphocytes continue
What is the clonal selection hypothesis?
Lymphocytes upon interacting with forgein antigen differentiate into effector cells and memory cells which bear the same receptors (clonal expansion)
