Adaptive Immune Response Flashcards
How does a T cell kill a pathogen
An APC has to process the antigen - T cell can then bind and become active. Cytotoxic T cells kill the pathogen
Naive T cells cannot produce a response
Apc interacting with t lymphocyte (naive - not been activated by antigen yet)
amp gies 3 pieces of info
• invader
• what it looks like
• type o immune response
What are the features of APCs?
Features of Antigen Presenting Cells
• Strategic location (B and T cell interaction)
- Skin (SALT)
- Mucous membranes (GALT, NALT, BALT, GUALT)
- Lymphoid organs (Lymph nodes, spleen)
- Blood circulation (plasmacytoid and myeloid DCs)
• Pathogen capture - Phagocytosis (whole microbe) - Macropinocytosis (soluble particles) • Diversity in pathogen sensors (PRRs) - Extracellular pathogens (bacteria) - Intracellular pathogens (viruses)
Name different types of APC, their location, and the type of T cll they present to
Dendritic cells (lymph nodes, mucous membranes, blood) - naive T cells
Langerhans cells (skin) - naive T cells
Macrophages (various tissues) - effector T cells
B cells (lymphoid tissues) - effector T cells & naive T cells
Describe what happens once the APC recognises the pathogen
- Dendritic cells sense microbe PAMPS - tell T cells to activate the humoral immunity - best response to combat extacellular microbes
- antibodies - means there is complement activation and phagocytosis
How is a virus removed?
- viruses replicate inside cells - viral protein ins ide the cells dendritic cells have receptor
- only way to clear infection is to kill viral infection cells - kill all viral infected cells - cytotoxic cells
- hla??? Human version?? Mhc = mammalian??
What are class 1 and class 2 molecules on mhc/hla
Class I molecules Found on all nucleated cells - HLA A/B/C
Class II molecules Found on dendritic cells, macrophages, B cells - HLA-DP/DQ/DR
What are key features of MHC class i and ii molecules?
Key features of MHC class I and class II molecules
• Co-dominant expression
- Both parental genes are expressed
-> ↑ number of different MHC molecules
• Polymorphic genes
- Different alleles among different individuals
-> ↑ presentation of different antigens/microbes
• Main function
- MHC Class I: present peptides from intracellular microbes - MHC Class II: present peptides from extracellular microbes
• The more diverse the molecule the better ,the more diverse the microbe the immune response can be mounted against
• co dominant - 6 from each parent
• different alleleic varying - increase type of mucus - increase recognition - increases bility to activate T cells
Describe the structure of mhc class i and ii molecules
• Peptide binding cleft - Variable region with highly polymorphic residues • Broad specificity - Many peptides presented by the same MHC molecule • Responsive T cells - MHC class I recognized by CD8+ T cells - MHC class II recognized by CD4+ T cells
What are the 2 antigen processing pathways
Endogenous and exogenous
• Both self and non-self peptides are presented
• All peptides from the same microbe are presented by different MHC molecules
• Susceptibility to infections depends on the types of MHC molecules
What is the endogenous pathway
- When proteins produced in the cytoplasm - labelled for degradation - targeted - degrade by proteasome - uptaken by transporters - get into ER - expression of host Mhc class 1 - if you have right match for right mhc - makes a complex - complex shifted to cell surface - limitations.- if you dont have right Mhc, wont be able to present the right peptide
- Mhc class.1 on all cells - call cells can get infected
What is the exogenous pathway
• Exo - antigen always in vesicle - vesicles fused with lysosomes - gives small peptides - fuse with another vesicle - Mhc class 2 waiting there - if there is a right match be peptide and much 2 - stable and expressed at the cell surface
What are ltnps?
Some patients called Elite controllers or long-term nonprogressors (LTNP)
can control viral replication
What is the difference between slow/rapid progress or
Slow - mhc molecules present key peptides for the survival of the virus - effective T cell response
Rapid - mhc molecules present mutated peptides less critical for the virus - poor recognition by T cells so poor T cell response
What are the clinical problems with mhc molecules
• Major causes for organ transplant rejection
- HLA molecules mismatch between donor and
recipient (Allograft) - Graft-Versus-Host reaction (GVH)
• HLA association and autoimmune disease
- Ankylosing spondylitis
• HLA-B27 -> 90% of patients - Insulin-Dependent Diabetes Mellitus
• HLADQ2 -> 50-75% of patients
What are intracellular/extracellular microbes and whats the difference
Extracellular Microbes - Bacteria - Parasites - Worms - Fungi -> mhc class ii -> cd4 +t cells -> humoral (b cells nd complement)
Intracellular Microbes - Viruses - Bacteria - Protozoa
-> cd4 + T cells -> cell dependent immunity (b cells and complement)
cd8 + T cells -> cytotoxic T cells
What are costimulatry proteins
?
What’s the difference between the T cell response to intracellular and extracellular microbes?
See slide
What’s are the acaracteristics of the antibody response
When host in contact - immunoglobulin produced - subsequent encounter - main igg bc it is best antibody response bc it can get deep into tisse
ratio between igg and igm can tell u if its chronic or acute
second response is faster and stronger - much more igg than igm. See listening for graph
What are the fucntions of IgG
IgG Fc-dependent phagocytosis
Complement activation
Neonatal Immunity
Toxin/virus neutralization
What are the fucntions of IgA
Mucosal immunity
What are the functions of IgE
Immunity against helminths
Mast cell degranulation (allergies)
What are teh fucntions of IgM
Complement activation
What are medical advances derived from the study of tha adaptive immune response
• Disease prevention
- vaccination
• Immunoglobulin therapies
- immune deficiencies
• Immediate protection
- passive immunisation
• Diagnostic tests (antibody-based)
- infectious diseases
- autoimmune diseases
- blood type and hla types
