Effector T Cells Flashcards
How can many different antigens be recognised by MHC as theres only 2 of these?
There are many different alleles for many genes and therefore polymorphism and polygeny both contribute to the diversity of MHC molecules expressed by an individual .
Can you inherit MHC haplotypes?
Yes
Gene conversion is not the same as what?
Genetic recombination
Can people have the same MHC?
No
What are immature Dendritic cells?
Phagocytes
Where are immature DC found?
Lymphoid organs and peripheral tissues
What are the two types of DC?
Conventional and plasmacytoid
What do conventional DC’s do?
Ingest and digest microbes and generate peptide antigens
Present on MHC to activate T cells with cognate TCR in secondary lymphoid tissues.
Produce cytokines in response to danger PAMPs by PRR engagement to activate other cells appropriately.
What do conventional DC 1 notice and produce?
Intracellular pathogens - they produce IL-12 and present to CD8 T-cells.
What do conventional CD2 cells notice and produce?
Extracellular pathogens and produce IL-12, IL-6 and TGF-beta to present to naive CD4+ T cells
What are the routes antigens are produced and show in DC?
Receptor mediated phagocytosis
Marocpinocytosis
Viral Infection
Cross-presentation after phagocytic or macropinocytic uptake
Transfer from incoming dendritic cells
What is the pathogen presented, MHC molecule loaded and type of naive T cell activated in receptor mediated phagocytosis?
Extracellular bacteria, fungi,
MHC2
CD4 T cells
What is the pathogen presented, MHC molecule loaded and type of naive T cell activated in macropinocytosis?
Extracellular bacteria, soluble antigens, virus particles.
MHC class 2
CD4 T cells
What is the pathogen presented, MHC molecule loaded and type of naive T cell activated in viral infections?
Viruses
MHC 1
CD8
What is the pathogen presented, MHC molecule loaded and type of naive T cell activated in cross presentation?
Viruses
MHC 1
CD8 T cells
What is the pathogen presented, MHC molecule loaded and type of naive T cell activated when transfered from incoming DC to resident DC?
Viruses
MHC 1 and MHC 2
CD 8 T cells and CD4 T cells
increased expression and co stimulatory molecules
What does antigen recognition result in?
Increased CCR7 expression and co-stimulatory molecules CD80/CD86 to enhance longevity of existing MHC 2 expression.
What binds CCR7?
CCL21 and CCL19
What forms a netwoek in the T cell zones in lymphoid tissue to enable interactions between naive T cells and DC?
Fibroblast reticular cells
What is produced in the fibroblast resticular cells which allows CCR7 bearing T cells and DC cells to meet?
CCL21 and CCL19
What happens when the T cell and the DC meet?
T cell initially bind APCs through low affinity LFA-1:ICAM-1 interactions and this signals to LFA-1 which causes a conformational change in LFA-1 increasing affinity and cell-cell contact
What forms when T-cells and DC meet?
Immunological synapse
What is Wiskott-Aldrich sydrome (X-linked)?
Increased tendency to bleed caused by a significantly reduced number of platelets. It is characterised by recurrant bacterial, vial and fungal infections. Also eczema of the risk and increased risk of developing severe autoimmune disease.
Where is WASP expressed in and what does it do?
Hematopoietic cells and plays a crucial role in actin cytoskeleton remodelling.