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HLA allelic variation 333 HLA class I molecules
5'
GLO
B2
Proteasome
Genes
TAP-1
TAP-2
HLA allelic variation
Genomic analysis has identified specific individual allelic
variants to explain HLA associations with rheumatoid arthritis,
type I diabetes mellitus, multiple sclerosis, and celiac disease.
A minimum of six α and eight β genes are arranged in
distinct clusters, termed HLA-DR, -DQ, and -DP, within the
HLA class II genes. DO and DN class II genes are related, but
map outside DR, DQ, and DP regions. The two types of dimers
along the HLA cell surface HLA-DR class II molecules
consist of either DRα polypeptide associated with DRβ 1
polypeptide or DR with DRβ 2 polypeptide. Structural variation
in class II gene products is linked to functional features
of immune recognition, leading to individual variations in histocompatibility,
immune recognition, and susceptibility to disease.
The two types of structural variations are (1) among DP,
DQ, and DR products in primary amino acid sequence by as
much as 35% and (2) individual variations attributable to different
allelic forms of class II genes. The class II polypeptide
chain possesses domains that are specific structural subunits
containing variable sequences that distinguish among class II
α genes or class II β genes. These allelic variation sites have
been suggested to form epitopes that represent individual
structural differences in immune recognition.
HLA-B
A class I histocompatibility antigen in humans that is
expressed on nucleated cells. Tissue typing to define
HLA-B antigens employs lymphocytes.
HLA-B27-related arthropathies
Joint diseases that occur with increased frequency in individuals
who are HLA-B27 antigen-positive. Juvenile rheumatoid
arthritis, ankylosing spondylitis, Reiter’s syndrome,
Salmonella-related arthritis, psoriatic arthritis, and Yersinia
arthritis belong to this group.
HLA-C
A class I histocompatibility antigen in humans that is
expressed on nucleated cells. Lymphocytes are employed
for tissue typing to determine HLA-C antigens. HLA-C
antigens play little or no role in graft rejection.
HLA class I
Refer to MHC genes and class I MHC molecules.
HLA class I molecules
The term used to describe MHC class I molecules in humans.
A2
Short Arm of Chromosome 6
C4A Factor B
C4B C2
HLA-DP HLA-DQ HLA-DR HSP-70 LTβ LT TNF HLA-B
HLA-C
B1 A1 B2 A2 B3 B1 A1 B1 B2
HLA-X
B3
HLA-E HLA-A HLA-G
HLA-J HLA-H
MHC genes encode the major histocompatibility antigens that are expressed on cell membranes. MHC genes in the mouse are located at the H-2 locus on
chromosome 17, whereas the MHC genes in man are located at the HLA locus on the short arm of chromosome 6.
B9
A
HLA-F
A schematic backbone structure of human class I histocompatibility antigen
(HLA-A 0201) complexed with a decameric peptide from hepatitis B nucleocapsid
protein (residues 18–27). Determined by x-ray crystallography..
3'
H