HLA-major histocompatibility

The P450c21 gene (CYP21) is located in the HLA major histocompatibility complex on the short arm of chromosome 6 (6p21.3) and is comprised of 10 exons spaced over 3.1 kb (Car-roll et al., 1985). CAH due to P450c21 deficiency is inherited as a monogenic autosomal recessive trait closely linked to the HLA complex. Thus, siblings with 21-hydroxylase deficiency are almost always HLA identical. Indeed,... 

DHEAS Dehydroepiandrosterone sulfate HLA Major histocompatibility (MHC) locus... 

Since all members of this family of RNA phages have homologous coat proteins, their subunits are expected to have the same three-dimensional structure. It remains to be seen if the MS2 fold is also present in any other unrelated viruses. The fold is so far unique for the MS2 subunit, but similar structures have been observed in other proteins such as the major histocompatibility antigen, HLA, which was discussed in Chapter 15. 

The human leucocyte antigen (HLA) system is the general name of a group of genes in the human major histocompatibility complex (MHC) region on human chromosome 6 (mouse chromosome 17) that encodes the cell-surface antigen-presenting proteins. 

Group of transmembrane proteins engaged in the presentation of small peptide fragments to T-cells. Two classes of Major histocompatibility complex (MHC) molecules exist both of which are encoded by a highly polymorphic gene cluster. MHC class I and class II proteins present peptide fragments to CD8+ and CD4+ T-cells, respectively. The human MHC is also known as HLA, the murine MHC as H-2 complex. 

Family history of RA. Genetic studies demonstrate a strong correlation between RA and the presence of major histocompatibility complex class II human leukocyte antigens (HLA), specifically HLA-DR1 and HLA-DR4.4,5 HLA is a molecule associated with the presentation of antigens to T lymphocytes. 

Human leukocyte antigens (HLA) Groups of genes found on the major histocompatibility complex, which contain cell-surface antigen-presenting proteins. The body uses HLA to distinguish between self-cells and non-self-cells. 

Ironically, SE or TSST-1 concentrations that cause T-cell proliferation do not always correlate with receptor affinity. For instance, SEE binds HLA-DR with 100-fold lower affinity relative to the very similarly structured SEA however, SEE stimulates T-cell proliferation to equivalent levels as SEA. The dose-response curves for cytokine and chemokine production in vitro by staphylococcal superantigen-stimulated cells are also very similar despite differences in affmity/specificity for major histocompatibility complex class II and T-cell receptor V/3 molecules. Overall, these observations suggest that the biological effects of staphylococcal superantigens are induced at rather low, nonsaturating occupancy rates not readily classified by typical biokinetics. 

Fig. 14.3 Tumor necrosis factor (TNF) locus with some of the polymorphic sites known within the TNF locus. C2, C4, complement C2, C4 Ch, chromosome HLA, human leukocyte antigen HSP, heat shock protein LTA, lymphotoxin A LTB, lymphotoxin B MHC, major histocompatibility complex. (Reproduced from ref 74 by permission of Future Medicine Ltd.)...

The MHC proteins are named after the "major histocompatibility complex —the DNA segment that codes for them. Human MHC proteins are also known as HLA antigens ( human leukocyte-associated antigens). Their polymorphism is so large that it is unlikely... 

Finally, in this brief overview of lymphocyte defects, mention should be made of mutations affecting major histocompatibility-complex (MHC) Class II molecules. These mutations affect a multiprotein transcription factor complex that regulates the expression of MHC Class II molecules (121). Affected patients have undetectable levels of MHC Class II antigens HLA-DP, DQ, and DR on the surface of monocytes and B cells. Lack of these antigen-presenting molecules leads to impaired immune response. Affected individuals have moderate lymphopenia with a severely reduced number of CD4+ T cells and normal or increased numbers of CD8+ T cells. Since MHC molecules in the thymic epithelium play a key role in positive and negative selection of primitive T cells, selection of competent T cells is also affected in the absence of MHC Class II antigens. 

The major histocompatibility (MHC) class 1 molecule is composed of a heavy chain, e.g., HLA-B7, and a light chain, /32-microglobulin. To express MHC class 1, both subunits must be expressed in the same cell. The inclusion of the IRES allows both polypeptide chains of a complete MHC class I molecule to be... 

Bondy PK Disorders of the adrenal cortex, in Wilson JD, Foster DW (eds) Textbook of Endocrinology. Saunders, New York, 1985, pp. 816-890. Carroll MC, Campbell RD, Porter RR Mapping of steroid 21-hydroxylase genes adjacent to complement component C4 genes in HLA, the major histocompatibility complex in man. Proc Natl AcadSci USA 82 521-525,1985. 

Willcox, B. E., Thomas, L. M., and Bjorkman, P.J. (2003). Crystal structure of HLA-A2 bound to LIR-1, a host and viral major histocompatibility complex receptor. Nat. 

The cause of type 1 diabetes is not fuUy understood. An autoimmune attack (to the /3-cells of the pancreas) may be triggered by reaction to an infection, for example by one of the viruses of the Coxsackie virus family or German measles, although the evidence is inconclusive. Individuals may display genetic vulnerability an observed inherited tendency to develop type 1 diabetes has been traced to particular human leukocyte antigen (HLA) genotypes (the major histocompatibility complex (MHC) in humans is known as the HLA system). Environmental factors can also strongly influence expression of type 1 diabetes. 

The role of the immune system in the pathophysiology of Graves disease is well established. A considerable amount of information links the human major histocompatibility complex (human leukocyte antigen [HLA]) with Graves disease. For instance, several HLA types, such as HLA-B8 and HLA-DR3, are associated with this disorder. Graves disease in the Japanese has been found to be associated with HLA-B35, whereas in patients of Chinese... 

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