What are the key players in adaptive immunity?
- T cell
- Antigen presenting cells
- Tumour cells
- Pathogens (bacteria, virus, fungi)
Identify and describe the two types of microbes found in the body
- Extracellular microbes which replicate outside of the cell
- Intracellular microbes which replicate inside the cell
Differentiate between the antigen presentation of extracellular and intracellular microbes respectively
- Extracellular microbes → humoral immunity
- Intracellular microbes → cell-dependent immunity
What are the strategic locations of APC's ?
- Skin (SALT)
- Mucous membranes (BALT, NALT, GALT, GUALT)
- Lymphoid organs (lymph nodes, spleen)
- Blood circulation (plasmacytoid and myeloid DCs)
How do APC's capture pathogens?
- Phagocytosis (whole microbe)
- Macropinocytosis (soluble particles)
Provide some examples for the different types of microbes
- Extracellular pathogens: bacteria, parasites, worms, fungi
- Intracellular pathogens: viruses, bacteria, protozoa
What are the components involved in humoral immunity?
What are the components involved in cell-dependent immunity?
- Cytotoxic T lymphocytes
Identify the different types of APC's found in the body
- Dendritic cells
- Langerhans cells
- B cells
Where are dendritic cells found and which cells do they present to?
- Location: lymph nodes, mucous membranes, blood
- Presentation: naive T cells
Where are Langerhans cells found and which cells do they present to?
- Location: skin
- Presentation: naive T cells
Where are macrophages found and which cells do they present to?
- Location: various tissues
- Presentation: effector T cells
Where are B cells found and which cells do they present to?
- Location: lymphoid tissues
- Presentation: effector and naive T cells
Where are Class I and Class II MHC found respectively?
- Class I molecules are found on all nucleated cells
- Class II molecules are found on dendritic cells, macrophages & B cells (APC's)
What does MHC stand for and what is the gene complex encoding it?
- Major Histocompatibility Complex
- Human Leukocyte Antigen (HLA)
Identify and describe two key genetic features of MHC class I and class II molecules
- Co-dominant expression – both parental genes are expressed → increase in the number of different MHC molecules
- Polymorphic genes – different alleles among different individuals → increased presentation of different antigens/microbes
What is the main function of MHC molecules?
- MHC class I: present peptides from intracellular microbes and are recognised by CD8+ T cells
- MHC class II: present peptides from extracellular microbes and are recognised by CD4+ T cells
Describe the structure of MHC molecules
- Peptide binding cleft: variable region with highly polymorphic residues
- Broad specificity: many peptides presented by the same MHC molecules
What are the two different antigen processing pathways?
In two steps, explain the response for slow-progressor HIV-infected individuals
⇒ MHC molecules present key peptides for the survival of the virus (unmutated)
⇒ Effective T cell response
In three steps, explain the response for rapid-progressor HIV-infected individuals
⇒ MHC molecules present mutated peptides (less critical peptides for the virus)
⇒ Poor recognition by T cells
⇒ Poor T cell responses
Identify two of the clinical problems associated with MHC molecules
- Major causes for organ transplant rejection i.e. HLA molecules mismatch between donor and recipient (allograft)
- HLA association with autoimmune disease e.g. Ankylosing spondylitis, Diabetes Mellitus Type I
Outline the features of T lymphocytes in terms of:
- Antigen receptor
- Types of T cells
- Antigen receptor: T cell receptor (TCR)
- Types of T cells: CD3+, CD4+, CD8+
Illustrate microbe processing and presentation in humoral immunity
Illustrate microbe processing and presentation in cell-dependent immunity
Explain the activation of the right T helper cells (TH) response
Illustrate T cell response to intracellular microbes
Explain T cell response to extracellular microbes
Briefly describe the characteristics of antibody response
State the immune functions of the IgG and IgA antibodies
- IgG – phagocytosis, complement activation, neonatal immunity
- IgA – mucosal immunity