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C receptor type 1 (CR1, CD35) is present in a soluble form in plasma (sCR1). Soluble CR1 was measured with a specific ELISA assay in normal individuals and in patients with different diseases. The mean serum concentration of sCR1 in 31 normal donors was 31.4 +/- 7.8 ng/ml, and was identical in plasma. An increase in sCR1 was observed in 36 patients with(More)
Complement receptor 1 (CR1) is present on erythrocytes (E-CR1), various leucocytes, and renal glomerular epithelial cells (podocytes). In addition, plasma contains a soluble form of CR1 (sCR1). By using a specific ELISA, CR1 was detected in the urine (uCR1) of normal individuals (excretion rate in 12 subjects, 3.12 +/- 1.15 micrograms/24 h). Contrary to(More)
Vesicles released from human E by Ca(2+)-loading, ATP-depletion, or storage are enriched in several glycosylphosphatidylinositol-anchored proteins such as acetylcholinesterase (AchE) and decay-accelerating factor (DAF). As a result of this, the remaining E are depleted of these proteins. We analyzed whether vesiculation induced by ATP-depletion in vitro was(More)
Factor D is an essential enzyme of the alternative pathway of complement. Its plasma concentration increases approximately tenfold in end-stage renal failure (ESRF). To analyze its metabolism in humans, we injected purified radiolabelled factor D into 5 healthy individuals and 12 patients with various renal diseases or renal failure. Fractional metabolic(More)
Since autoantibodies (Abs) to cytokines may modify their biologic activities, high-affinity binding factors for interleukin-1 alpha (IL-1 alpha BF) were characterized in human sera. IL-1 alpha BF was identified as IgG (1) by sucrose density-gradient centrifugation followed by immunodiffusion autoradiography, (2) by ligand-blotting method, (3) by ligand(More)
The two forms of human C4 were compared in their haemolytic activity and in their capacity to mediate inhibition of immune complex precipitation in human C4 deficient sera. Whereas haemolysis by C4B was 3.2 fold more efficient than by C4A, C4A was 1.7 fold more efficient at inhibiting immune precipitation than C4B. Thus the biological properties of the two(More)
The number of complement receptor type 1 (CR1; CD35) on human erythrocytes (E) decreases during normal in vivo aging. Patients with acquired immunodeficiency syndrome (AIDS) have an acquired deficiency of CR1 on E. The possible mechanisms responsible for the loss of CR1 from E include the release of small vesicles from the E membrane and proteolytic(More)
The mechanisms responsible for cold-induced precipitation of mixed cryoglobulins are not well understood. A mixed cryoglobulin IgM kappa/IgG (type II) of a patient with Sjögren's syndrome was studied because of its unique properties. This cryoglobulin precipitated in serum but not in serum containing 10 mM EDTA. The cryoprecipitation was shown to require(More)
Complement prevents the formation of insoluble immune complexes (inhibition of immune precipitation (IIP], and solubilizes preformed immune aggregates (solubilization (SOL]. Since the mechanism of complement activation differs in these two reactions, it is possible that they differ also in the amount of complement fragments released, in particular the(More)
To examine whether the ability of complement to form soluble immune complexes plays a role in preventing immune complex-mediated diseases, we analyzed the capacity of complement to inhibit immune precipitation (IIP) and to solubilize preformed immune aggregates (SOL) in 23 sera of patients with various hypocomplementemic states, and we correlated the(More)