Lecture 6- Adaptive Immune Response Phase 1 Flashcards
Why are antigen presenting cells so important for T cell function?
A naive T cell wont be activated if it comes across a pathogen. It must have the pathogens antigens presented to it by an antigen presenting cell and get activated that way
Endogenous vs exogenous microbes?
Endogenous come from the body whereas exogenous come from outside it
What are the important features of antigen presenting cells?
Strategic location- in mucosa associated lymphoid tissue such as skin and tonsils. Lymphoid organs and blood.
Pathogen capture- phagocytosis
Diversity- Pathogen recognition receptors for extracellular and intracellular pathogens
Extracellular and intracellular pathogen examples?
Extracellular= bacteria
Intracellular= virus
PRR examples?
Extracellular ones like toll like receptor 1 for gram- positive bacteria
Toll like receptor 3 for double stranded DNA viruses
Examples of antigen-presenting cells?
Dendritic cells- lymph nodes, blood, mucous membranes
Langerhans cells- skin
Macrophages- various tissues
B cells- lymphoid tissues
Difference between Major histocompatibility complex (MHC) and human leukocyte antigen (HLA) molecules?
No difference
MHC class 1 vs MHC class II molecules?
MHC class 1 are located in all nucleated cells and deal with intracellular microbes. Eg virus enters cell and is broken down into peptides. If matched with MHC I antigenic peptide will be displayed on cell surface for CD8+ T cell to recognise and destroy cell. This is the endogenous pathway
MHC class II molecules are only present in antigen presenting cells such as langerhans cells and macrophages. Eg bacteria are phagocytosed and fused with an endosome, broken down and antigens presented at cell surface by MHC II for CD4+ T cells. This is the exogenous pathway
Key features of MHC/HLA molecules?
Peptide binding cleft can bind various molecules.
Have broad specificity for many different antigens
MHC class I CD8+ T cells MHC class II CD4+ T cells
Why is it important that no two individuals have the same set of MHC molecules?
Prevents everyone being wiped out by one microbe
HIV individuals and MHC molecules?
Slow progress ours and rapid progressors.
Slow progressors have MHC molecules for genes that cannot be mutated and so they can defend themselves against virus better as these genes will be recognised and presented for T cells
Problem with MHC molecules?
Can cause organ transplant to be rejected
Associated with autoimmune disease
What relevance do MHC molecules have to attraction?
Attracted to those with different MHC molecules to you as offspring will have better immunity
Why are lymphocytes in chronic inflammation?
Because t lymphocytes are primary cells of adaptive immune response
