Antigen Presentation and MHC Molecules Flashcards
the major histocompatibility complex is also called what in humans?
human leukocyte antigen complex (HLA)
how are MHC class I and class II molecules the same?
- act as a cell-surface vessel for holding or displaying fragments of antigens
- T-alpha-beta engage with class I and II via their T cell receptors on the cell surface
How are MHC class III molecules different from class I and II?
- region encodes complement proteins and tumor necrosis factor
- functions are unrelated to antigen presentation
what is a HAPLOtype?
all the alleles encoded by the genes in the complex are inherited in a set one from mother and one from father (co-dominantly expressed)
why are the MHC haplotypes used for paternity and signature/fingerprint testing?
they are highly polymorphic within the human race meaning each of the molecules is very different between persons
how many different classes of class I and class II molecules are there in a person?
6 different class I
12 different class II
what is the structure of the MHC Class I molecule?
- a peptide with 3 domains ( a1, a2 and a3), a transmembrane C terminal and a beta-2 microglobulin
what does the a1 and a2 domains of a MHC class I molecule form? what does it carry?
forms a cleft that carries antigenic peptides of 8-10 amino acids one at a time that are very polymorphic
do MHC molecules have broad specificity?
yes, many different peptides can fit the same MHC molecule
what binds to the a3 domain of MHC class I molecules?
CD8 molecules on T cells
are the amino acids in the a3 domain of class I MHC molecules polymorphic?
no
what does it mean that the MHC class I molecules are the classical transplant antigens?
MHC class I molecules are encoded by the highly polymorphic HLA genes, specifically HLA-A, HLA-B, and HLA-C and these molecules are the primary targets of the immune system during organ transplant rejection.
which class of MHC molecules are used for paternity testing?
class I
which class of MHC molecules present endogenous antigens to CD-8 cytotoxic T-cells?
class I
what is the structure of the MHC Class II molecule?
- an alpha peptide with two domains (a1 and a2) and a transmembrane C terminal
- a beta peptide with two domains (b1 and b2) and a transmembrane C terminal
what does the a1 and b1 domains of a MHC class II molecule form? what does it carry?
forms a cleft that carries antigenic peptides of 10-20 amino acids one at a time that are very polymorphic
what binds to the b2 domain of MHC class II molecules?
CD4
are the amino acids in the a1 and b1 domain of class II MHC molecules polymorphic?
yes
are the amino acids in the a2 and b2 domain of class II MHC molecules polymorphic?
no
where are MHC class II found and what do they present?
found on antigen presenting cells and present antigens to CD4 helper T cells
what are professional antigen presenting cells (APC)?
cells that constitutively express MHC class II molecules
what are the types of professional APC?
- macrophage and macrophage like cells (langerhans and dendritic cells)
- B lymphocytes
what are occasional presenter cells?
cells that express MHC class II molecules when induced
what are examples of occasional presenters?
- cytokines
- karatinocytes
- endothelial cells
- epithelial cells
what MHC class molecules present exogenous antigens and which one presents endogenous antigens?
- class I presents endogenous
- class II present exogenous
which class of MHC molecules present exogenous antigens to CD-4 T helper cells?
class II
CD-1 shares structural similarities to what MHC class molecule but functionally overlaps with ?
class I
class II
CD-1 molecules present what type of antigens to what cells?
lipid-containing antigens to NKT cells and T-gamma-delta
