Immunology II Flashcards
Where are CD28 and B7 located on?
CD28 is found on T cells. B7 is found on APC, such as activated macrophages.
What are the adhesion molecules involved in interaction of activated CD8 T cells with infected molecules?
LFA-1 on T cell interacts with ICAM on target cell.
What are the 3 proteins found in lytic granules released by cytotoxic T cells? State their function.
Perforin - Polymerises to form a pore in the bacterial cell membrane
Granzymes - Serine proteases which will activate apoptosis once inside the cytoplasm of the target cell
Granulysin - Induces apoptosis
What other 4 substances are released from activated cytotoxic T cells?
- IL-2: further stimulates the differentiation and proliferation of more CD8 T cells
- IFN gamma: blocks viral replication which will lead to viral death without cell death
- TNF alpha: activates and induces NO production
- TNF beta: activates macrophages, directly cytotoxic
What are the 3 molecules/cells activated by CD4 Helper T cells and what are they activated to do?
- CD8 T cell: kill virally infected cells (through release of IFN gamma)
- Activates macrophages to kill intracellular bacteria
- Activates B cells to activate neutrophils to remove extracellular bacteria and fungi
What are the actions of Th1, Th2 and Th17?
Th1: CMI. activates macrophages, targets intracellular infections. helps B cells in antibody production
Th2: Humoral. activates B cells, mast cells, eosinophils, targets extracellular parasites and also helps B cells in antibody production.
Th17: Amplify inflammation and attracts neutrophils to clear extracellular bacteria and fungi
Which is formed in the presence of infection, and which is formed in the absence of infection? Treg, Th17
Treg is formed in the absence of infection whereas Th17 is formed in the presence of infection.
What is targeted by macrophages? Is it extracellular or intracellular?
Macrophages remove intracellular pathogens.
What is targeted in B cell activation?
B cells kill extracellular bacteria and fungi (pathogens)
MHC I contains alpha or beta chain genes?
Alpha.
MHC II contains alpha or beta chain genes
Both alpha and beta gene
In direct or indirect allorecognition was non-self MHC involved?
Direct allorecognition.
Which (direct or indirect allorecognition) will there be fewer T cells activated?
Indirect allorecognition
Describe graft-versus-host-disease. How is it different from normal solid organ transplant rejection?
In GVHD, the donor organ (usually a bone marrow), will perceive the recipient tissues as foreign and rejects it. However, in solid organ transplant rejection, the recipient rejects the transplanted organ/graft.
Hyperacute rejection occurs mainly from?
Blood group mismatches
What is the difference between hyperacute and acute rejection?
Hyperacute rejection occurs immediately when the graft is first inserted.
In acute rejection, the graft is accepted for the first 10 - 13 days, and is then rejected.
What type of rejection occurs in acute rejection as opposed to chronic rejection?
In acute rejection, there is direct cytotoxic effect after the first 10 - 13 days.
In chronic rejection, the progress is slow, with gradual laying down of fibrous tissue.
Which phagocyte is responsible for eliminating IgE coated parasites such as helminths?
Eosinophils
Are neutrophils seen in the blood stream in healthy individuals?
Yes. But in infected individuals, neutrophils will be seen in the infected tissues.
Do leukocytes adhere to the walls of arteries?
No, only adheres to and rolls along the walls of veins.
Where are naive T and B cells activated?
In peripheral lymphoid organs, such as lymph nodes, spleen, GALT, BALT, and MALT (Gut, Bronchial, Mucosal-associated lymphoid tissues).
CD40 ligand is on T cells or B cells? When is CD40 ligand and CD40 interaction involved?
CD40 ligand is on T cells. CD40 is on B cells.
CD40 ligand-CD40 interaction occurs in isotope class-switching of B cells.