Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To explore the biochemical basis for maintaining immunological tolerance by functional inactivation of self-reactive B lymphocytes, transgenic mice carrying rearranged anti-lysozyme immunoglobulin transgenes and a lysozyme transgene were used as a source of large numbers of tolerant self-reactive B cells. Antigen receptors of the IgD isotype were expressed at normal levels on tolerant B cells, contained the heterodimeric MB1/B29 signalling component of the receptor complex and were structurally indistinguishable from IgD on nontolerant B cells. In contrast, cell surface expression of IgM receptor complexes on tolerant B cells was greatly reduced, despite normal expression of mRNA encoding the receptor components. Three-fold fewer immunoreactive mu heavy chains were detectable after a short period of biosynthetic labelling and the immunoreactive mu chains produced were paired with kappa light chains and assembled normally into intact receptor complexes containing the MB1/B29 heterodimer. Nascent IgM receptor complexes nevertheless failed to be processed into an endoglycosidase H-resistant form in the tolerant B cells and thus appeared to be selectively blocked in their transport from the endoplasmic reticulum to the medial Golgi. These findings demonstrate that intracellular trafficking of antigen receptor complexes is regulated by exposure to receptor stimuli at the cell surface causing a long-lasting decrease in surface receptor expression on tolerant B cells.
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PMID:A selective defect in IgM antigen receptor synthesis and transport causes loss of cell surface IgM expression on tolerant B lymphocytes. 811 96

Granulocytic sarcoma (GS) is an uncommon and localized extramedullary tumor composed of immature granulocytic cells. Most GS reported in large series were not associated with overt acute myelogenous leukemia. Gastric perforation occurred during prednisolone therapy in a 72-year-old Japanese male with a four-month history of a myelofibrosis-like state. Subtotal gastrectomy was performed for a suspected gastric ulcer perforation. Gastric histologic, immunohistochemical and cytochemical examination revealed diffuse infiltration by sheets of myeloblasts and promyelocytes with scant or moderately abundant cytoplasm including a few eosinophilic myelocytes. Bone marrow study done in one month after the operation disclosed refractory anemia with excess of blasts (RAEB). Leukemic transformation occurred two months later, and a subcutaneous tumor appeared on the forehead. The forehead tumor predominantly consisted of myeloblasts without evidence of maturation. Both the stomach and forehead tumors were examined immunohistochemically with a panel of monoclonal antibodies (LCA, L26, MT1, UCHL1, OPD4, LN-1, LN-2, LN-3, MB1, Leu-M1, PM) and polyclonal antibodies (lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin, S-100 protein, lactoferrin), as well as naphthol-ASD-chloroacetate esterase staining to investigate and characterize the reliable marks for GS, and the patient was diagnosed as GS. We found that gastric GS may occur in a myelofibrosis-like state followed by RAEB of myelodysplastic syndrome and that naphthol-ASD-chloroacetate esterase staining and immunohistochemical detection of MT1, lysozyme, and alpha 1-antitrypsin were the most reliable markers for confirming the diagnosis of GS.
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PMID:Unsuspected gastric granulocytic sarcoma in a patient with myelodysplastic syndrome. 870 73


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