T cells and co-ordinating the immune system Flashcards
(33 cards)
How can we differentiate between T cells?
Based on phenotype.
What are the phenotypes of T cells?
The molecules present within or external to the T cell.
What is CD and what is it used for?
Class differentiation antigens present on T cells which correlate to their function.
What is MHC restriction?
The specificity of MHC peptide transporter classes presenting antigen fragments to a specific T cell.
How does MHC I restrict?
Macrophage engulfs the pathogen in the ER where it is broken down into fragments into the cytosol which is carried by MHC I to present to CD8+ T cells.
How does MHC II restrict?
B cell antibodies bind to pathogen and forms a vesicle where it is degraded/ Macrophage takes in pathogen to form a phagosome where it is degraded. MHC II takes up antigen fragments in the endosome to present to CD4+ T cells.
What is the function of CD4+ Tfh?
T follicular helper cells produce IL-21 to help B cell activation into plasma cells producing antibodies for antigen affinity. It is involved in the formation of germinal centres in lymphoid tissue.
What is the function of CD4+ Tfh?
T follicular helper cells produce IL-21 to help B cell activation into plasma cells producing antibodies for antigen affinity. It is involved in the formation of germinal centres in lymphoid tissue.
What is the function of CD4+ Th1 and CD8+?
Type 1 immunity to initiate phagocytic killing of a microbe causing tissue damage.
What is the function of CD4+ Th2?
Type 2 immunity against helminths.
What is the function of CD8+ CTL?
Cytotoxic killer which destroys infected host cells.
What is the function of CD4+ Th17?
It recruits neutrophils for activation and directs autoimmunity. Releases IL-17.
What is autoimmunity?
Antibodies target self cells.
What is the function of CD4+ Treg?
Inhibits the response of T cells.
What is IL-2 and what T cell produces it?
T cell survival and clonal expansion produced by Th2
What is IFNy and what T cell produces it?
Responsible for macrophage activation, produced by Th2 and CD8+ T cells.
What is IL-4 and what T cell produces it?
Regulating antibody production and haematopoeisis, released by Th2.
What is IL-17 and what T cell produces it?
Activation of neutrophils, produced by CD4+ Th17
What is Tfh and what T cell produces it?
B cell differentiation into plasma cells, produced by CD4+ Tfh.
How do T cells activate and differentiate?
Interaction with the TCR by antigen processing, costimulation to determine it is pathogen derived by the pathogen itself or a dendritic or phagocytic cell and then cytokine release which stimulates differentiation.
How can TCR be blocked?
By immunosuppressant drugs such as tacrolimus and cyclospoirin. They act in the cytoplasm to bind to the phosphotase enzyme calcineurine and prevent calcium-associated activation for transcription.
What are the consequences of clonal expansion?
Clonal selection by dendritic cells survey for T cell with complementary TCR, Once selected this undergoes clonal expansion and differentiates from naive T cells into memory cells which can reside in lymphoid tissue and increase response following immunisation or effector cells which have functions depending on their differenitation. Memory cells can become effector cells and vice versa. Eventually they die.
How are T cells cleared?
Tregs which release granzymes.
How does memory affect clonal expansion?
Increases the rate of clonal expansion.
