Session 5-Adaptive Immune Response Flashcards
What are the strategic locations of antigen presenting cells?
- skin
- mucous membranes (GALT, NALT=nasal, BALT, GUALT)
- lymphoid organs (nodes and spleen)
- blood circulation
What are the two methods of pathogen capture by antigen presenting cells?
- phagocytosis (whole microbe)
- macropinocytosis (soluble particles)
Explain the diversity in pathogen sensors in antigen presenting cells
- extracellular pathogens (bacteria)
- intracellular pathogens (viruses)
What are the different types of antigen-presenting cells?
- dendritic cells
- Langerhans’ cells
- macrophages
- B cells
Where are dendritic cells present?
Lymph nodes
Mucous membranes
Blood
What do dendritic cells present to?
Naive T cells (T cells that haven’t encountered pathogen)
Where are Langerhans’ cels found?
Skin
What do Langerhans’ cells present to?
Naive T cells
What do macrophages present to?
Effector T cells
Where are B cells found?
Lymphoid tissues
What do B cells present to?
Effector and naive T cells
What is the human version of the major histocompatibility complex (MHC)?
Human leukocyte antigen (HLA)
What are the two different classes of MHC/HLA?
1) Class I molecules - found on all nucleated cells
2) Class II molecules - found on dendritic cells, macrophages, B cells
What are the key features of MHC Class I and Class II molecules?
1) co-dominant expression: both parental genes expressed -> increased number of different MHC molecules
2) polymorphic genes: different alleles among different individuals -> increased presentation of different antigens/microbes
What is the main function of MHC class I molecules?
Present peptides from intracellular microbes
What is the main function of MHC class II molecules?
Present peptides from extracellular microbes
Describe the structure of MHC class I and class II molecules
1) peptide binding cleft: variable region with highly polymorphic residues
2) broad specificity: many peptides presented by same MHC molecule
3) responsive T cells
Which T cell recognises MHC class I molecules?
CD8+ T cells
Which T cells recognise MHC Class II molecules?
CD4+ T cells
What a does susceptibility to infections depend on?
Types of MHC molecules
What are the clinical problems with MHC molecules?
- organ transplant rejection
- HLA association and autoimmune disease
Which type of immunity does the activation of CD4+ T cells lead to in response to extracellular microbes?
Humoral immunity (antibodies and complement)
Which type of immunity does CD4+ T cells lead to in response to intracellular microbes?
Cell-dependent immunity
Which cells are activated in response to CD8+ T cells?
Cytotoxic T cells
Why are costimulatory signals needed?
For T cell activation
What role does eosinophils have against extracellular microbes?
Killing of parasites
What are the roles of B cells against extracellular microbes?
Phagocytosis
Complement
What are the roles of mast cells against extracellular microbes?
Local inflammation
Allergies
What is the immune function of IgG?
Toxin/virus neutralisation
