Adaptive immunity Flashcards
Where are antiigen presenting cells found?
Sites of entry
Skin, mucous membranes (In the lymphoid tissue)
Lymphoid organs
Blood circulation
What 3 features enhance the ability of antigen presenting cells?
THeir strategic location
Pathogen capture (Can phagocytose)
Diversity in Pattern recognition receptors
Four types of Antigen-presenting cell? Where are each found? Which cells do they present to?
Dendritic cells-Lymph nodes, mucous membrane, blood-present to Naive T cells
Langerhans cells- Skin- present to Naive T cells
Macrophages- Various tissue- Effector T cells
B-cells- Lymphoid tissue- present toEffector and Naive T cells
How does a apc recognise a pathogen?
A pathogen has Pathogen associated molecular patterns (PAMPs) on its surface that the pathogen recognition receptors (PRRs) on the apc can recognise
How is the exogenous pathway trigger?
By extracellular microbes
Describe the exogenous pathway
antigen in a vesicle
vesicle fuses with lysosome
Degrades the antigen into antigenic peptides
Vesicle fuses with another vesicle that contains MHC class 2 proteins
The antigenic peptide locates its matching MHC and this MHC takes the peptide to the cell surface
Describe the endogenous pathway
Antigen enters the cytoplasm
Ubiquitin tags self and non self proteins for degradation
proteasome does the degrading
The antigen peptides are then transported into the ER via a specific transporter
MHC class 1 proteins are produced in the ER
antigen peptides locate matching MHC class 1 protein
transport peptide to the surface
What types of T cells does MHC class 1 and 2 activate?
Class 1- CD8+
Class 2- CD4+
What three structures are necessary in order to fully activate a T cells
The correct, matching T cell receptor to the antigenic peptide
Either CD4+ or CD8+ dependent on class 1 or 2
Coo-Ctimulatory protein (CD80/86–>CD28)
What type of T cell differentiates into Cytotoxic T cell?
CD8+
What is required for the CD8+ T cell to fully differentiate into cytotoxic t cells?
Both CD4+ and CD8+ T cells must be acctivated
How does a cytotoxic T cell kill a virally infected cell?
Detects the MHC class 1 presenting the antigen peptide Releases perforins and ganzymes to kill the cell
What two types of t cells can CD4+ T cells differntiate into?
TH2 and TH17
What cells do the TH2 and TH17 activate?
TH2: B cells, Mast cell and eosinophils
TH17: Neutrophils
Describe the primary and secondary antigen response
Primary: First contact to pathogen
IgM is mostly produced
Secondary: IgG main antibody. Note that IgM still produced to the same level
