Antigen recognition Flashcards
why are adaptive immue cells important?
Adaptive immune cells have to:
Recognise foreign antigen
Destroy or produce products that can destroy the pathogen
Develop immune memory
Disseminate immunity around the body
what do B cells do and where are they produced?
produce antibodies for extracellular antigens
they are produced in the bone marrow
what do T cells do and where are they produced?
identify cells with intracellular antigens
they are produced in the thymus
what is immune recognition driven by?
by protein (antigen receptor) ligand (antigen) interactions
what is the challenge in immune recognition?
the ligands (anitgens) are very diverse and can evolve rapidly to avoid detection.
antigen recogintion involves diverse, somatically generated and clonally expressed T and B cell antigen receptors.
what is the function and difference between CD8+ and CD4+ T cells.
CD8+ cytotoxic T cells can recognise virus infected or cancerous cells. They induce cell lysis and produce antiviral cytokines
CD4+ helper T cells provide critical help to B cells and CD8+ t cells
What is MHC restriction?
activation of T cells depends on simultaneous recognition of both foreign peptide fragments and self MHC molecules. The requirement for the TCR to engage with both peptide and MHC concurrently is called MHC restriction.
what is the purpose of MHC molecules?
act as antigen display receptors. they display peptide and lipids representing antigens that come from within cells.
What does it mean when we say HLA genes are polymorphic?
Multiple forms of each gene exist within the population (termed alleles).
What does it mean when we say HLA genes are polygenic?
Multiple genes with the same function but slightly different structures, resulting in a broad range of peptide binding specificities.
what is a HLA gene?
Human leukocyte antigens (HLA) are genes in major histocompatibility complexes (MHC) that help code for proteins that differentiate between self and non-self
Why do humans have such diversity in their HLA genes?
MHC polymorphisms encode differences in the peptide-binding groove, which increases the diversity of peptides that can be presented within a population.
What is the total theoretical number of combinations of HLA class I and II molecules?
HLA-I(1.2 x 10^7) x HLA-II(1.8 x 10^10) = 2.25 x 10^17
How does the degree of diversity in MHC influence disease susceptibility in populations?
Different MHC haplotypes may confer varying levels of protection against or susceptibility to infectious or autoimmune diseases.
What does it mean when we say that MHC genes are co-dominantly expressed?
Both copies of a gene inherited from each parent are expressed, resulting in each individual carrying two sets of linked HLA haplotypes.
