Interferons, antibodies and T-cell development Flashcards
(37 cards)
What are toll like receptors? Innate immune system
Proteins found on the cell membrane or in vesicles that respond to foreign pathogens.
What are interferons?
Signalling molecules that alert other host cells there is a foreign pathogen and synthesise antipeptides and also instruct macrophages and NK cells to begin to become activate and proliferate.
How are interferons produced?
Virus enters the cell and migrates to the nucleus in attempt to intergrate itself into the host cell’s genome. When the host genome is damaged this secretes the transcription factor IRF which activates a gene which is converted into mRNA and translated into proteins and interferons are produced.
What are the three types of interferons?
Alpha, beta and gamma
Which cells secrete IFN-Y?
Lymphocytes or other immune system cells
How is protein kinase R produced?
Alpha and beta interferons diffuse into adjacent tissue cell and activate a specific gene which produces protein kinase R (antiviral peptide).
What is the function of protein kinase R?
Inhibits virus replicating in cell
What is the function of IFN-Y?
Released from the infected cell and binds to IFN-Y receptors on nearby macrophages and induces a signalling cascade instructing the macrophage to proliferate, becomes bigger and increases expression of MHC-1 and MHC-2.
How are natural killer cells activated?
By alpha and beta interferon
Which type of cell secretes antibodies?
Plasma cells
What are the role of IgG antibodies?
Initiates the complement system via the classical pathway when binding to an antigen resulting in cell lysis (MAC), oponisation by production of C3b and pro-inflammatory chemotaxic agents.
Also causes neutralisation by preventing the virus or bacterium attaching to host cell and phagocytosis and precipitation.
What form are IgA antibodies produced in?
As a dimer
Where are IgA antibodies found?
In the skin, saliva, mucosa lining
Which antibodies have a role in passive immunity?
IgA antibodies are found in breast milk and IgG antibodies are passed through the placenta especially in the third trimester.
When are IgM antibodies usually secreted?
In primary response to the pathogen, therefore a good indicator for early diagnosis.
What is the role in of IgM antibodies in type 2 hypersensitivity?
Can bind to multiple antigen binding sites when in the monomeric form causing glucination.
Can IgM also induce the complement system?
Yes, it can initiate causing a downstream pathway of MAC, opsonisation and pro-inflammatory chemotactic agents.
Where is the monomeric form of IgE antibodies found?
In the respiratory tract mucosa
Urogenital structures
Lamina propria
Lymphatic tissue
Describe the role of IgE antibodies.
IL-4 activates and causes proliferation of plasma cells which produces IgE which binds to the allergen. Together with the allergen they bind to the FcER1 receptors on mast cells and continued binding of the antigen-antibody complex causes degranulation of the mast cell releasing leukotrienes, histamines and prostaglandins. Histamines bind to the H1 receptors on vascular smooth muscle causing vasodilation and for the blood vessels to become leaky causing oedema. It also causes contraction of bronchial smooth muscle which causes wheezing and difficulty breathing.
What is the role of IgD antibodies?
Acts as a B cell receptor
How does plasma undergo changes from producing IgM to IgG antibodies?
Due to somatic hypermutation where different cyotkines activate different genes which causes different production of antibodies.
Does IgM or IgG production change in the secondary infection?
IgG massively increases.
Explain the two types of immunity.
Passive immunity: antibodies didn’t have to be produced by fighting off an infection, was given them.
Active immunity: antibodies acquired by fighting off the infection.
What are some examples of naturally acquired passive immunity?
IgG antibodies through the placenta or IgA antibodies in Mother’s milk.
