Immunology - Monoarticular Joint Pain Flashcards
HLA
Human Leukocyte Antigen
MHC
Major Histocompatibility Complex
Where is the immunological self encoded in
The HLA/MHC genes
Recognised by T-cells
MHC proteins
Presents pathogen peptides to T-cells
Self peptides are loaded on these
How are viral proteins obtained
Broken down by proteolysis
Characteristics of MHC/HLA genes
Highly polymorphic
Produce proteins that vary greatly in individuals —> pop. w/ diversity in their immune systems
What do HLA genes define
A genetic locus that varies between individuals
If the peptide or MHC are wrong the T-cell is activated - occurs during infection and in tissue rejection
Where do memory B cells divide
In the germinal centre
How do T-cells leave the thymus
W/ rearranged genes and ability to recognise Ag but most don’t recognise self
Differentiate in thymus - VDJ recombination. Self-reactive T-cells are removed in the thymus
What happens when T cell precursors haven’t rearranged genes
Don’t express T-cell markers and cannot bind Ag
Maturation of T cells
Progenitor T cells enter thymus where adhesion molecules on medullary epithelial cells stimulate proliferation and gene rearrangement
Thymic medulla cells use MHC to educate T-cells
Eliminatation of self-reactive T-cell
How are T cells educated
MHC cells are used by thymic medulla cells to present self proteins (peptides) to immature T-cells
What happens if immature T-cells have weak binding for MHC self-peptides
They survive
+ve selection
What happens if immature T-cells have strong binding for MHC self peptides
They die
-ve selection
Central tolerance
Elimination of self-reactive T-cells in the thymus
Retained in bone marrow
