WK 1- INNATE AND ADAPTIVE IMMUNE RESPONSES Flashcards
What is innate immunity
Non specific immune response and present before presence of a pathogen, immune response generated is always the same (despite the pathogen), involves barriers such as physical barriers (skin and mucous), cellular responses and soluble mediators (cytokines, complements, kinins)
What is adaptive immunity
Involves formation of antibodies-> is a delayed response, is leukocytes driven and specific to the invading pathogen
What does immunogenic mean
Any molecule that on its own can elicit an adaptive immune response
What cells are involved in innate immunity
innate lymphoid cells, monocytes, macrophages, natural killer cells, mast cells, dendritic cells, neutrophils
What cells are involved in adaptive immunity
leukocytes, mast cells, T cells, dendritic cells, B cells
What are antigen presenting cells
aka accessory cells-> take antigen from pathogen and display it with MHC on their surface. Include cells like macrophages, DC and NK cells
What is a PAMP
Pathogen associated molecular pattern-> are molecules that a cell possesses, such as lipopolysaccharides and DNA/RNA, that identify a pathogen as being foreign, allowing it to be attacked by the body. They are not found on eukaryotic cells (self-cells)
What is a DAMP
Danger associated molecular pattern-> include things such as acidity and toxic molecules, that are released by the body during trauma and can trigger an immune response, just like PAMP
What is PRR
Pathogen recognition receptors-> are receptors that a sensor cell possesses (macrophages, DC, mast cells) or that is secreted, that recognise PAMPs and turn on genes associated with inflammation and immune response
(inflammation will aid in removal of the pathogen)
What are the 3 types of PRR
- Extracellular
- Intracellular
- Secreted
What are examples of extracellular PRRs
- Manos and Scavenger receptors; cause phagocytosis of pathogen and lysozomal degradation
- Toll-Like receptors (TLR4); pathogen will bind to the receptor and cause signals to be sent to the nucleus causing release of cytokines (IL-1, IL-6, TNFa), chemokines and interferons that will aid in killing pathogen
What are examples of intracellular PRRs
- NOD receptors; when pathogen binds inside cell it will trigger release of cytokines (such as TNFa, IL-1, IL-6) which cause inflammation and destruction of pathogen, or they will trigger apoptosis
What are examples of secreted PRRs
- Complements; secreted by the liver, when they interact with pathogens they will trigger the complementary cascade
What is the complementary cascade
Is part of the innate immune system and involves soluble proteins travelling in blood in their inactive form-> when they bind to a pathogen they will become activated and cause the complementary cascade to occur and result in: opsonization, creation of membrane attack complex that cause the pathogen to lyse, and initiation of an immune response through recruiting immune cells
What are the 3 pathways that form the complementary cascade
Classical, Lectin and Alternative pathways
Describe the classical pathway of the complementary cascade
Plays a role in the adaptive immune response-> it is activated when antibodies bind to antigen of a pathogen
Describe the lectin pathway of the complementary cascade
Initiated by mannos binding lectin protein binding to carbohydrates on the cell surface of a pathogen
Describe the alternative pathway of the complementary cascade
Triggered by C3b directly binding to a pathogen
What protein/complement factor do all 3 pathways converge on
C3b
What is opsonisation
Process by which complement coats the outside of a cell surface of a pathogen, tagging it for phagocytosis
What are 4 types of acute phase proteins
1) serum amyloid protein
2) C-reactive protein
3) fibrinogen
4) mannose binding lectin
What cytokine acts on the liver to stimulate production of acute phase proteins
IL-6
What are examples of primary lymphoid tissue
Thymus (T cells) and bone marrow (B cells)
What are examples of secondary lymphoid tissue
Spleen, lymph nodes, MALT
What are membrane attack complexes
groups of complement proteins create a hole in a pathogen, allowing for inward movement of fluid and for the pathogen to eventually lyse
What is an opsonin
anything that can form a bridge between a phagocyte and a microbe–> allows for opsonisation
eg. C3b
What are antigens
Surface markers present on all cells that allow the body to recognise them as being self or non-self–> antigens include blood grouping antigens (RhD, ABO), MHC and toxins
What are antibodies
Are functional proteins that allow for the binding of antigens an complements. Antibodies can be found bound to a cell or in body fluids. Eg. IgM, IgA, IgE, IgD, IgG
What do antibodies do
Antibodies bind to antigens and enhance the immune response through; preventing attachment of pathogens, enhancing phagocytosis, neutralising toxins
