| T-cell antigen receptors | Receptors present on T-cells that interact with both processed antigen and major histocompatibility antigens simultaneously. (05 Mar 2000) |
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| Fc receptors | <immunology> Receptors for the Fc portion of immunoglobulins. Fc_R (30 kD) is the receptor for serum and secretory IgA1 or IgA2 and is expressed on most myeloid cells and subpopulations of T and B-cells. Fc_RI (CD64) High affinity receptor (72 kD on gels) for monomeric IgG1 found on monocytes, macrophages and some neutrophils. The extracellular portion has three immunoglobulin superfamily C2 domains, in contrast to Fc_RII, Fc_RIII that have only two. Involved in antibody dependent cell killing and in clearance of immune complexes. Fc_RII (CD32) Low affinity receptor 40 kD) for aggregated IgG that exists in several sub types coded by three closely related genes, A, B and C. All forms are found on monocytes, the B forms (that are alternatively spliced) are found on B-cells, the A and C forms are present on neutrophils. Binding of aggregated IgG will trigger phagocytosis and the oxidative burst in neutrophils. Fc_RIII (CD16) is the low affinity receptor (50-80 kD on gels) for aggregated IgG. It is found in transmembrane and GPI linked forms. The transmembrane form associates with the _ subunit of Fc_RI or the TCR_ chain and on B-cells with the _ chain of Fc_RI. Has structural similarity with Fc_RI, Fc_RII and Fc_RI_. Binding of aggregated IgG or IgG antigen complexes mediates phagocytosis or antibody dependent cellular cytotoxicity. Fc_RI is a heteromeric high affinity receptor for IgE found on mast cells and basophils. The _ chain (45-65 kD on gels, 25 kD of polypetide) is N glycosylated and has two immunoglobulin C2 loops in addition to the transmembrane domain, the _ chain (32 kD) has four transmembrane domains, the _ subunit is a homodimer (8 kD monomer) identical to the _ subunit of CD16 and has similarity with _ and _ chains associated with the T-cell receptor. Binding of antigen to the IgE Fc_R complex triggers the release of histamine and various inflammatory mediators. Fc_RIIa & b CD23) Low affinity receptor (45 kD) for IgE. Both a and b are present on mature B-cells, the b form on monocytes, IL-4 activated macrophages, eosinophils, platelets and dendritic cells. The protein has a C type lectin domain that mediates IgE binding and can be cleaved from the membrane to yield an active soluble form. (18 Nov 1997) |
| low-density lipoprotein receptors | Receptors on the surface of cells, especially liver cells, which bind to low density lipoprotein and promote clearance of LDL from the plasma. (05 Mar 2000) |
| acrocephalosyndactyly type 1 | <paediatrics> An inherited disease (autosomal dominant) or a spontaneously occurring disease characterised by a peaked head and unusual facial appearance, due to the premature closure of the cranial sutures. A skull X-ray can confirm the diagnosis and treatment is surgical. Inheritance: autosomal dominant. (27 Sep 1997) |
| Alzheimer type I astrocyte | Enlarged frequently multinucleated astrocytes, seen in progressive multifocal leukoencephalopathy. (05 Mar 2000) |
| Alzheimer type II astrocyte | Enlarged astrocytes with vesicular nuclei and one or more small basophilic nucleoli, seen in hepatocerebral disease and Wilson's disease. (05 Mar 2000) |
| American Type Culture Collection | <cell culture> A key resource for cultured cells, located in Rockville, USA. (12 Dec 1998) |
| Antoni type A neurilemoma | <tumour> Relatively solid or compact arrangement of neoplastic tissue that consists of Schwann cells arranged in twisting bundles and associated with delicate reticulin fibres; the nuclei of the Schwann cells are frequently grouped in parallel rows (so-called palisades), and the nuclei and fibres sometimes form exaggerated tactile corpuscles, called Verocay bodies. (05 Mar 2000) |
| Antoni type B neurilemoma | <tumour> Relatively soft or loose arrangement of neoplastic tissue that consists of Schwann cells in a haphazard or nondescript type of arrangement among reticulin fibres and tiny cystlike foci; fat-laden macrophages may be observed in some of the larger neoplasms. (05 Mar 2000) |
| arthus-type reaction's | Reaction's in man and other species that result from the same basic immunologic (allergic) mechanism which evokes, in the rabbit, the typical Arthus phenomenon. See: immune complex disease. (05 Mar 2000) |
| avian adenovirus type 1 proteinase | <enzyme> 206 aa residues of which 66% are homologous to human ad2 emzyme embl/genbank l13161 Registry number: EC 3.4.22.- Synonym: aavl proteinase, aavl endopeptidase (26 Jun 1999) |
| basic personality type | An individual's unique, covert, or underlying personality propensities, whether or not they are behaviourally manifest or overt, personality characteristics of an individual which are also shared by a majority of the members of a social group. (05 Mar 2000) |
| Becker type muscular dystrophy | A muscular dystrophy that has many of the clinical features of Duchenne muscular dystrophy e.g., symmetrical involvement of first the pelvicrural muscles and then the pectoral girdle and proximal upper extremity muscles; pseudohypertrophy, especially of the calf muscles but with a much later age of onset (35-45 years), and more benign course. X-linked inheritance. (05 Mar 2000) |
| Becker type tardive muscular dystrophy | Muscular dystrophy of late onset, often in the second or third decade, with relatively mild course; X-linked recessive inheritance; perhaps allelic with Duchenne's dystrophy, but milder and not a genetic lethal. Compare: Duchenne dystrophy. Synonym: Becker type tardive muscular dystrophy. (05 Mar 2000) |
| blood type | The specific reaction pattern of erythrocytes of an individual to the antisera of one blood group; e.g., the ABO blood group consists of four major blood types: O, A, B, and AB. This classification depends on the presence or absence of two major antigens: A or B. Type O occurs when neither is present and type AB when both are present. The blood type is the genetic phenotype of the individual for one blood group system and may be determined using different antisera available for testing. See Blood Groups appendix. (05 Mar 2000) |