Adaptive Immunity (see Diagram As Well ) Flashcards
What are the 3main features of APCs?
- Strategic location(interaction with B and T lymphocytes)
- Pathogen Capture(phagocytosis, macropinocytosis (soluble particles))
- Diversity in PRR: intra/extracellular
Where are APCs located?`
- Skin
- Mucous membrane (MALT: GALT,NALT,BALT,GUALT)
- Lymphoid organs
- Blood circulation
Which APCs activate naive T cells ? And where are they located
Dendritic (lymph nodes ,mucous membrane ,blood)
Langherans (skin)
Which APCs interact with effector T cells ?
Macrophages
B cells
How do APCs capture and present antigen?
Capture thanks to PAMPS and PRRs
Present on MHC (major histocompatibility complex)
What immune actors get activated in Humoral immunity ?
Antibodies
Complement
Phagocytosis
What immune actors get activated in Cell-dependent immunity ?
Cytotoxic T Lymphocytes (from CD8+)
Antibodies
Macrophages
How can APCs recognise bacteria and viruses ?
PRRs outside and inside APCs
What are MHC molecules and what is their function ?
- Proteins encoded by polymorphic genes present on cell surface
- Function is to bind antigen derived from self or non-self Microorganism and display it on cell surface for recognition by T-cells for activation or not of adaptive immune response
Where can you found class I MHC molecules and what peptides do they display ?
- Class I present on all nucleated cells (including APC)
- Present peptides from intracellular microorganism
Where can you found class II and what peptides do they display ?
Only on APCs(dendritic,macrophages,B cells )
Display peptides from extracellular organisms
Which chromosome code for MHC molecules ?
Chromosome 6
Which genes code for class I MHC molecules ?
HLA-a, b , c
Which genes code for class II MHC molecules ?
HLA-DR,DQ,DP
Which adaptive immune cell recognise Class I MHC molecules ?
CD8+ T cells
CD4+ T cells recognise which MHC molecules ?
Class II
Describe the endogenous antigen processing pathway
Intra cellular organism :
- in cytoplasm
- all protein ,self and non-self tagged by ubiquitin
- degraded by Proteasome
- antigen transported to ER by TAP (transporter associated with antigen processing)
- antigen binds to MHC class I and expressed on surface
Describe the exogenous antigen processing pathway
Extracellular organism
- phagocytosis
- endosome with peptide fuses with Vesicle containing MHC class II molecules
- expressed on surface
How do T lymphocytes recognise the antigen ?
And the MHC receptor ?
- T cell Receptor (TCR)
- CD4 and CD8 recognise MHC classII and classI
What are costimulator signals ? Give eg
Molecules present on APCs that help full activation of T lymphocytes
Eg : CD80/86
What are the different types of T helper cells, which pathway and which cytokines do they secrete ?
-TH1 : intracellular , TNF and IFNg
- TH2 : extracellular , IL4 ,5 ,10
- TH17 : extracellular , IL17
Which Serum AB concentration is the highest in first contact with a pathogen ? What s its characteristic ?
IgM
Stick to antigen to activate complement
What is isotype switching ?
Second contact with antigen , monoclonal antibody IgG has higher concentration in serum , overall AB concentration higher
What is the benefit of isotype switching and IgG ?
Faster, stronger , longer and higher affinity AB response
IgG can go to extracellular site and opsonise or neutralise (virus)in addition to complement activation
