The first component of complement, C1, was isolated unactivated from human serum by repeated additions of di-isopropyl phosphorofluoridate during isolation. The unactivated subcomponents were also isolated, and evidence is given that the three subcomponents C1q, C1r and C1s account wholly for the activity of component C1 in serum. No evidence could be found for a fourth subcomponent, C1t. The a...

The classical complement pathway contributes to the natural immune defense against pathogens and tumors. IgG antibodies can assemble at the cell surface into hexamers via Fc:Fc interactions, which recruit complement component C1q and induce complement activation. Biophysical characterization of the C1:IgG complex has remained elusive primarily due to the low affinity of IgG-C1q binding. Using I...

The radial immunodiffusion assay overestimates the C1q in serum. Here we describe a convenient, accurate procedure for measuring C1q in 250 microL of dialyzed serum. This method is based on our previous findings that all C1q in serum precipitates with the euglobulin fraction and that all other serum proteins containing hydroxyproline are excluded from this fraction. Because C1q is 4.3% hydroxyp...

Backgrounds: Autoantibodies against C1q are strongly linked to immune-complex disorders like systemic lupus erythematosus (SLE). Although anti-C1q antibodies have received much interest in the recent years, their biological functions remain unclear. Aim and objectives: The main aim of this study was analyze phenotype at first presentation during follow-up Qena university hospital. Subjects meth...

Dendritic cells (DCs) are the most potent antigen-presenting cells capable of priming naïve T-cells. Its C-type lectin receptor, DC-SIGN, regulates a wide range of immune functions. Along with its role in HIV-1 pathogenesis through complement opsonization of the virus, DC-SIGN has recently emerged as an adaptor for complement protein C1q on the surface of immature DCs via a trimeric complex inv...

Preeclampsia (PE) is a life-threatening, pregnancy-induced disease and a leading cause of maternal and fetal morbidity and mortality. Despite considerable research, the causes of PE remain unclear, and there is no effective treatment. Studies in animal models that resemble this complex pregnancy-related disorder may help to identify possible therapies for PE. Complement component C1q has an imp...

PURPOSE The degeneration of retinal ganglion cells (RGC) in the glaucomatous retina is accompanied by activation of the classical complement cascade. The purpose of this study was to evaluate whether complement component C1q binding and activation of the complement cascade in the glaucomatous retina requires the presence of immunoglobulins. METHODS Experimental glaucoma was induced in normal ...

To evaluate the relationship between tumor burden and circulating immune complexes (IC) in malignant melanoma, we tested sera collected serially from 15 normal donors and 53 patients. Forty-eight of these had Stage III or IV disease at the outset of the study. The median survival time (MST) of ten patients with Stage IV disease whose sera contained C1q-binding IC at the outset of the study was ...

Although studies have suggested a role for the complement system in the pathophysiology of spinal cord injury (SCI), that role remains poorly defined. Additionally, the relative contribution of individual complement pathways in SCI is unknown. Our initial studies revealed that systemic complement activation was strongly influenced by genetic background and gender. Thus, to investigate the role ...

OBJECTIVE An early diagnosis of lupus nephritis (LN) has an important clinical implication in guiding treatments of systemic lupus erythematosus (SLE) in clinical settings. In this study, the diagnostic values of circulating autoantibodies to C1q alone or in combination with other markers for accessing active SLE and LN were evaluated. METHODS The diagnostic value of anti-C1q autoantibodies f...