Thrombin-mediated platelet membrane-specific uptake of C3 and C5 was demonstrated by radiolabeled components and was visualized electron microscopically utilizing a ferritin marker conjugated to monospecific antibody to each component. The role of complement in thrombin-induced platelet function was determined. Though complement was not essential for thrombin-induced platelet aggregation and re...

The role of complement in the pathogenesis of autoimmune hemolytic anemia (AIHA) has been controversial and may depend on a number of factors, including the affinity and isotype of the pathogenic antibodies involved. We have recently shown that mouse erythrocytes deficient in the membrane C3 regulatory protein, complement receptor 1-related gene/protein y (Crry), but not decay-accelerating fact...

The amount of the third component of complement (C3) bound to red cells of patients with the cold agglutinin syndrome was determined by a quantitative assay, measuring the fixation of the first component of complement by anti-C3. Abrupt reduction in the serum concentration of cold agglutinin by plasmapheresis markedly decreased the hemolytic rate, but the amount of C3 bound to circulating cells...

The complement system is tightly regulated to safeguard against tissue damage that results from unwanted activation. The key step of C3 cleavage to C3b is regulated by multiple mechanisms that control the initiation and extent of activation. This study demonstrated that C3b:plasma protein complexes form in the fluid-phase during complement activation. Several different plasma proteins displayed...

Hepatocytes which had been isolated from the livers of Charles River rats were cultured in vitro. The cells were shown to synthesize albumin and the complement components C4, C2, C3 and B. Pulse-label studies with [35S]methionine showed that C4 and C3 were synthesized as single polypeptide chains. Pro-C4 did not appear to be converted into the plasma form of C4 intracellularly, whereas cell lys...

Examination of the EST database of the light organ of the Hawaiian bobtail squid Euprymna scolopes revealed a sequence with similarity to complement C3. RACE yielded the full open reading frame of this protein. Analysis of the resultant sequence revealed that Es-C3 (E. scolopes-C3) has conserved residues and domains known to be critical for C3 function. The gene encoding C3 was expressed in all...

BACKGROUND Anorexia nervosa carries the highest mortality rate of any psychiatric disorder. Even the most critically ill anorexic patients may present with normal 'standard' laboratory values, underscoring the need for a new sensitive biomarker. The complement cascade, a major component of innate immunity, represents a driving force in the pathophysiology of multiple inflammatory disorders. The...

The role of complement in the pathogenesis of autoimmune hemolytic anemia (AIHA) has been controversial and may depend on a number of factors, including the affinity and isotype of the pathogenic antibodies involved. We have recently shown that mouse erythrocytes deficient in the membrane C3 regulatory protein, complement receptor 1–related gene/ protein y (Crry), but not decay-accelerating fac...

Of the 30 distinct complement proteins recognized to date, C3 is probably the most versatile and multifunctional molecule known, interacting with at least 20 different proteins. It plays a critical role in both pathways of complement activation and participates in phagocytic and immunoregulatory processes. Structural and functional analysis of C3 from different species, in addition to phylogene...

During its differentiation in the insect vector to a stage infective for the mammalian host, Trypanosoma cruzi becomes resistant to lysis by the alternative pathway of complement. To elucidate the mechanism of complement evasion, we studied control of complement activation on the surface of the noninfective epimastigote and the infective culture-derived metacyclic trypomastigote stages (CMT) of...