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Results for “Complement System Proteins”

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At least 163 records · Page 9Linked to original sources
PubMed1982

An immunological evaluation of pleural effusions in systemic lupus erythematosus.

Of 59 patients with pleural effusions, four had systemic lupus erythematosus. Assessments of pleural antinuclear antibody, rheumatoid factor, anti-DNA antibody and hemolytic complement after corrections for pleural protein and corresponding serum values were of no diagnostic significance. Pleural analyses did not contribute diagnostic information beyond that defined by serum markers.

Blood Proteins↗
PubMed1991

Phospholipid-anchored and transmembrane versions of either decay-accelerating factor or membrane cofactor protein show equal efficiency in protection from complement-mediated cell damage.

Decay-accelerating factor (DAF) is a glycosyl-phosphatidylinositol (GPI)-anchored membrane protein that protects cells from complement-mediated damage by regulation of the C3 convertase. To investigate the role of the GPI anchor in the function of DAF, the cDNA encoding human DAF was expressed by transfection in Chinese hamster ovary (CHO) cells. Testing of these DAF transfectants in an antibody plus human complement-mediated cytotoxicity assay demonstrated that DAF protects these cells from cytotoxicity, and that the level of protection increases with expression of surface DAF. A cDNA construct encoding a transmembrane version of DAF (DAF-TM) protects CHO transfectants from cytotoxicity with equal efficiency to DAF. This DAF-TM construct used the TM and cytoplasmic domains of membrane cofactor protein (MCP); an alternate TM version of DAF constructed with the TM and cytoplasmic domains of HLA-B44 showed equivalent protection. The protection from cytotoxicity involved a decrease in the deposition of C3 on the cell, consistent with the effect of DAF on the C3 convertase. A second pair of anchor variants, MCP and a GPI-anchored construct, MCP-PI, were also equivalent in their complement protection. The equivalent function of GPI-anchored and TM versions of a protein was not expected based on the hypothesized increased lateral mobility of GPI-anchored proteins, which should confer a functional advantage in contacting ligand, in this case, C3b or C4b, on the cell surface. These data suggest either that GPI-anchored and TM versions of a protein have equal lateral mobility in the membrane, or else that increased lateral mobility is not advantageous to DAF or MCP in carrying out their complement inhibitory roles. Furthermore, DAF and MCP demonstrated approximately equal protection of cells from complement-mediated cytotoxicity, suggesting that DAF and MCP provide overlapping levels of protection to cells against damage mediated by the complement system.

Animals↗
PubMed1979

Acquired C1 inhibitor deficiency in a case of lymphosarcoma of the spleen. Reversal of complement abnormalities after splenectomy.

A patient with an extensive lymphosarcoma of the spleen without involvement of other lymphoid organs and hypogammaglobulinaemia showed the characteristic complement profile of an acquired C1-inhibitor deficiency. Both functional and immunochemical studies revealed extremely low levels of the inhibitor of C1-esterase. Correction of the low levels of early acting complement components and of the low C1-inhibitor level followed the splenectomy. In vitro tests showed that lymphosarcoma tissue pieces or cells were able to interact with complement, resulting in a depletion of the haemolytic activity. These findings provide evidence that tumour cells were responsible for the abnormalities of the complement system.

Aged↗