antigen presentation and MHC Flashcards
what region of HLA gene codes for class II MHC proteins
D region of HLA gene
what regions of HLA gene encode for class I MHC proteins
regions A, B, and C
MHC gene expression is
codominant and polymorphic
MHC haplotype
total set of MHC genes on each chromosome
inherit one haplotype from each parent
how many class I and class II genes does an individual receive
3 different class I and 3 different class II genes from EACH parent total of 6 different class I and 6 different class II MHC proteins are inherited
role of MHC proteins
T lymphocytes only respond to antigen when it is expressed on an antigen presenting cell (APC) in conjunction with MHC proteins
narcolepsy gene
HLA-DR2
ankylosing spondylitis gene
HLA-B27
how to increase success of long term graft survival in organ transplantation
match HLA types
immunosuppressive drugs
why is it a problem that RBCs don’t have MHC molecules
in malaria, when RBCs are infected, they cannot alert cytotoxic T cells that they are infected
beta 2 microglobulin is required for
cellular expression of alpha chain in class I MHC without beta 2, can't get MHC I to cell surface
where are MHC proteins
surface of all nucleated cells
not on erythrocytes (no nucleus) or corneal epithelial cells
where are MHC class I proteins
surface of all nucleated cells
not on erythrocytes (no nucleus) or corneal epithelial cells
where are MHC class II proteins
surface of APCs (dendritic cells, macrophages, and B lymphocytes)
polymorphic
multiple variants of each gene exist in population
polygenic
multiple variants of one gene within an individual’s genome
structure of class I MHC
alpha and beta chains
alpha is longer than beta
beta 2 microglobulin is required for cellular expression of alpha chain
cleft accommodates peptides that are 9-11 amino acids in length
structure of class II MHC
alpha and beta chains
equal in length
cleft accommodates peptides that are 10-30 amino acids in length (because cleft is open at ends)
MHC restriction
CD8+ T cells recognize only protein fragments in cleft of class I MHC CD4+ T cells recognize only protein fragments in cleft of class II MHC
linear determinants
T lymphocytes can only recognize linear determinants because only linear can be processed by MHC proteins
gamma interferon
T lymphocyte is activated by APC
T cell produces gamma IFN
gamma IFN induces higher levels of class II MHC on APCs
gamma IFN also induces expression of class II MHC on epithelial, glial, mesenchymal, and vascular endothelial cells to aid in T cell activation
