Immunology 5th lecture Flashcards
T/F : No IgM remaining when secondary immune response + underlying concept
F: Always some IgM remaining in the organism. No immune response is pure (more precisely, this can mean never only 1 immunoglobulin class)
Where most B cells killed
Bone marrow (system similar to clonal selection/deletion / central immune tolerance in the thymus but less understood)
What happens during pure cell-mediated response
No pure cell-mediated response Always humoral component as well
What cells do viruses choose to infect
Cells they are specific to
3 antigen presenting cells
Macrophage, dendritic cells and B lymphocytes (so monocytes and B lymphocytes)
What happens to viruses (that is similar to the bacterial infection)
Are chewed up by dendritic cells and MHC II + epitope presented on surface
What kills viruses ultimately but what does that not stop from happening ?
Ultimately, T cytotoxic cells kill viruses, but there is still a humoral response
First cell involved in specificity of cell-mediated response
T helper cell 1
What TH1 does similarly to TH2 and what cytokines it releases
Recognizes MHC II + epitope with its TCR. Coreception between B7 (dendritic cell) and CD28 (on TH1)
How can cell-mediated response be downregulated similarly to the humoral response
T regulatory cells can stop it (just like TH cells - TH1 and TH2, have CTLA4 and PD-1 that will displace CD28 and B7) - peripheral tolerance
What cytokines TH1 releases
INF (interferon) and IL 2 (interleukin 2)
What cells Tc must bind for a proper cell-mediated response to start
No cell. We do not know whether there is a link between Tc and the dendritic cell (or a virus on it) and between Tc and TH1
Effect of INF and IL2 on Tc
Causes a further SPECIALIZATION and EXPANSION of the Tc cell clone
How Tc recognizes virally infected cells
All cells have MHC 1 on surface, virally infected ones will present MHC 1 + epitope
How Tc cell binds to virally infected cells and what does it do then and afterwards
Binds with its TCR on MH1 + epitope and kills the cell. Continues killing other infected cells after
What is absolutely necessary for a functional T cell (primordial importance)
Must recognize MHC molecules, otherwise destroyed
When development of T cell tolerance in thymus happens
In utero
3 mechanisms for the maintenance of immunological tolerance in adults
1) Ongoing thymic tolerance mechanisms as new T cell clones arise
2) T regul. cells inhibiting TH activation using CTLA4
3) Tolerance of the route of exposure (TOLEROGENIC MALT)
Proportion of allergies and region of the body where allergens are recognized
1/3 people = allergic. allergen (foreign entity) often seen in gut or bronchial tree
How allergies are conserved through evolution
Passed on genetically
Characteristic of TCR formation
Random (not caused by antigenic stimulation)
What CD4 helps for
(on TH1 and TH2 but NOT ON Tc) Bind to MHC II of MHC II + epitope complex, WHILE TCR BINDS TO OTHER PARTS OF THIS COMPLEX
What CD8 helps for
(on Tc cells) Bind to MHC I of MHC I + epitope complex, WHILE TCR BINDS TO OTHER PARTS OF THIS COMPLEX
How is it that virally infected cells can present an epitope of a virus on a MHC I on their surface
All cells do some phagocytosis/capable of digestion (but some better than others) (+ all cells have MHC I)
