Major Histocompatibility Complex Flashcards
in adaptive immune system for appropriate response to a foreign antigen…
lymphocytes must recog antigen be stimulated to divide and differentiate
on b cells what is antigen recognition mediated by
surface immunoglobulins
on T cells what is antigen recognition mediated by
T cell receptor
what do t cells recognise
parts of antigens that are expressed on cell surfaces
where might antigens come from
from pathogens that replicate within host cells (viruses)
may come from pathogens or their products that have been endocytosed from the extracellular fluid
what si detected by t cells
presence of t cells and foreign antigens
what are major histiocompatibilty complex molecules
pathogen derived peptides delivered to and presented at cell surface by specialised glycoproteins
where are MHC proteins encoded in
large cluster of genes on chromosome 6
what are recognised by recipient immune system in transplantation
MHC antigens
in humans what are MHC molecules referred to as
HLA
human leucocyte antigens
what ar the two classes of MHC family
class 1 n 2
what does class 1 consist of
HLA - A
HLA - B
HLA - C
what does class 2 consist of
HLA - DP
HLA - DQ
HLA - DR
what does both classes have in common
similar 3d structures
where is class 1 expressed
on all nucleated cells including leucocytes
where is class 2 expressed
only on leucocytes which present antigen to T cells (monocytes)
why indiv expresses only 2 forms of each protein co dominantly
one from mother one from father
what are the clinical implications
tissue grafting
diseases predisposed
forensic medicine
what are the tissue grafting implications
kidney transplants
skin grafts
bone marrow transplants
what are some of the predisposed diseases
chronic inflam of spine
HLA - DR4 rheumatoid arthritsu
sleep disorder
what sit he sttruure of class 1
alpha chain
beta 2 microglobulin
what is the structure of class 2
alpha chain and beta chain
in class 1 and 2 what do the sets of protein do
at mem - resemble immunoglobulin domains
away from mem - fold together to create long groove for antigenic peptide bonds
which class has peptide binding cleft more open
class 2
what does MHC present antigenic peptides to
T cells
what T cells do each of the classes present to
class 1 - Tc cells class 2 - Th cells
what happens in class 1
viral and cellular proteins broken down into peptides
cell infected with virus
MHC complexes cover cell surface
cytotoxic T cell recognises viral protein in MHC display as foreign and destroys
what in class 2 cll
processing compartment limited proteolysis
MHC class 2 and processed peptide
Th help to b cell
