| HLA complex | <immunology> The major histocompatibility complex in humans. See: human lymphocyte antigens. (05 Mar 2000) |
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| HLA | <immunology> A genetic fingerprint on white blood cells and platelets, composed of proteins that play a critical role in activating the bodys immune system to respond to foreign organisms. Acronym: HLA (16 Dec 1997) |
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| HLA-a1 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the a locus on chromosome 6. Individuals bearing this allele are more susceptible to hodgkin's disease. HLA-a1 is in linkage disequilibrium with HLA-b8 and HLA-dr3. (12 Dec 1998) |
| HLA-a2 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the a locus on chromosome 6. The HLA-a2 antigen is associated with recognition of the influenza a virus. (12 Dec 1998) |
| HLA-a3 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the a locus on chromosome 6. The allele occurs with increased frequency in individuals with idiopathic haemochromatosis. HLA-a3 is in linkage disequilibrium with HLA-b7 and HLA-dr2. (12 Dec 1998) |
| HLA-a antigens | <immunology> Polymorphic class I human histocompatibility (HLA) surface antigens present on almost all nucleated cells. at least 20 antigens have been identified which are encoded by the a locus of multiple alleles on chromosome 6. They serve as targets for T-cell cytolytic responses and are involved with acceptance or rejection of tissue/organ grafts. (12 Dec 1998) |
| HLA antigens | <immunology> A complex family of genetically inherited proteins which are found on the surface of cells throughout the body. They determine the match between patient and potential donor in bone marrow transplantation. These factors are inherited from the mother and father and so the chance of having the same HLA antigens between siblings is 1 in 4. See: human lymphocyte antigens. (20 Jun 2000) |
| HLA-b27 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the b locus on chromosome 6. It is strongly associated with acute anterior uveitis, ankylosing spondylitis, and reiter's disease. Increased frequency of antigen in: ankylosing spondylitis (90%), Reiter syndrome (90%), enteropathic arthritis (75%), psoriatic arthritis (60%) normal frequency: white: 8%, black: 4% (12 Dec 1998) |
| HLA-b35 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the b locus on chromosome 6. It is weakly associated with a number of diseases. (12 Dec 1998) |
| HLA-b7 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the b locus on chromosome 6. There is a weak association between the presence of the HLA-b7 antigen and the diseases of narcolepsy and idiopathic haemochromatosis. HLA-b7 is in linkage disequilibrium with HLA-a3 and HLA-dr2. (12 Dec 1998) |
| HLA-b8 antigen | <immunology> Human histocompatibility (HLA) surface antigen encoded by the b locus on chromosome 6. It is in linkage disequilibrium with HLA-a1 and HLA-dr3. This explains the fact that though HLA-b8 was originally associated with several diseases, including coeliac disease, dermatitis herpetiformis, and myasthenia gravis, their association with HLA-dr3 is now considered more significant. (12 Dec 1998) |
| HLA-b antigens | <immunology> Class I human histocompatibility (HLA) surface antigens encoded by more than 30 detectable alleles on locus b of the HLA complex, the most polymorphic of all the HLA specificities. Several of these antigens (e.g., HLA-b27, -b7, -b8) are strongly associated with predisposition to rheumatoid and other autoimmune disorders. Like other class I HLA determinants, they are involved in the cellular immune reactivity of cytolytic t lymphocytes. (12 Dec 1998) |
| HLA-c antigens | <immunology> Class I human histocompatibility (HLA) antigens encoded by a small cluster of structural genes at the c locus on chromosome 6. They have significantly lower immunogenicity than the HLA-a and -b determinants and are therefore of minor importance in donor/recipient crossmatching. Their primary role is their high-risk association with certain disease manifestations (e.g., spondylarthritis, psoriasis, multiple myeloma). (12 Dec 1998) |
| HLA-d antigens | <immunology> Human immune-response or class II antigens found mainly, but not exclusively, on B-lymphocytes and produced from genes of the HLA-d locus. They are extremely polymorphic families of glycopeptides, each consisting of two chains, alpha and beta. This group of antigens includes the -dr, -dq and -dp designations, of which HLA-dr is most studied; some of these glycoproteins are associated with certain diseases, possibly of immune aetiology. (12 Dec 1998) |
| HLA-dp antigens | <immunology> A group of the d-related HLA antigens (human) found to differ from the dr antigens in genetic locus and therefore inheritance. These antigens are polymorphic glycoproteins comprising alpha and beta chains and are found on lymphoid and other cells, often associated with certain diseases. (12 Dec 1998) |
| HLA-dq antigens | <immunology> A group of the d-related HLA antigens found to differ from the dr antigens in genetic locus and therefore inheritance. These antigens are polymorphic glycoproteins comprising alpha and beta chains and are found on lymphoid and other cells, often associated with certain diseases. (12 Dec 1998) |