The complement system enhances antibody responses to T-dependent antigens, but paradoxically, deficiencies in C1 and C4 are strongly linked to autoantibody production in humans. In mice, disruption of the C1qa gene also results in spontaneous autoimmunity. Moreover, deficiencies in C4 or complement receptors 1 and 2 (CR1/CR2) lead to reduced selection against autoreactive B cells and impaired h...

A new cluster of complement component genes, including C4BP, C3bR, and FH, is described. Family segregation data indicate that FH is linked to the genes for C4-bp and C4bR, previously reported to be linked and to maintain linkage disequilibrium. This cluster is not linked to the major histocompatibility complex, which contains the genes for the complement components, C4, C2, and factor B, or to...

Complement, a complex protein system, plays an essential role in host defense through bacterial lysis, stimulation of phagocytosis, recruitment of immune cells to infected tissue, and promotion of the inflammatory response. Although complement is most well-characterized in serum, complement activity is also present in the lung. Here we further characterize the complement system in the normal an...

OBJECTIVES To estimate the complement activating properties of monoclonal, monoreactive, and polyreactive IgM rheumatoid factors derived from Epstein-Barr virus transformed B cells isolated from peripheral blood and synovial tissue of patients with rheumatoid arthritis (RA). METHODS An enzyme linked immunosorbent assay (ELISA) was used to measure the activation of the classical pathway of com...

Abbreviations: sFlt-1: Soluble fms-Like Tyrosine Kinase-1; PlGF: Placental Growth Factor; 2DE: 2-Dimensional Gel Electrophoresis; MALDI: Matrix-Assisted Laser Desorption/Ionization; TOF: Timeof-Flight; LC: Liquid Chromatography; ESI: Electrospray Ionization; C8: Complement Component 8; C9: Complement Component; MAC: Membrane Attack Complex; C3: Complement Component 3; C5a: Complement Component ...

Systemic lupus erythematosus is characterized by dysfunctional clearance of apoptotic debris and the development of pathogenic autoantibodies. While the complement system is also involved in the disease no attempt has been made to generate a comprehensive view of immune complex formation from various autoantigens. We increased the complexity of autoantibody profiles by measuring the binding of ...

Levels of C4d, a fragment of C4 generated during activation of the classical complement pathway, were measured in the plasma of 77 patients with rheumatoid arthritis and 30 healthy subjects. Disease activity was judged according to Ritchie's articular index to be mildly active in 31 (group 1), moderately active in 29 (group 2), and severely active in 17 patients (group 3). Plasma levels of C3d,...

The importance of gene duplication for evolutionary diversification has been mainly discussed in terms of genetic redundancy allowing neofunctionalization. In the case of C4 photosynthesis, which evolved via the co-option of multiple enzymes to boost carbon fixation in tropical conditions, the importance of genetic redundancy has not been consistently supported by genomic studies. Here, we test...

Objective Complement plays a major role in SLE. Complement participation has been linked to disease activity and damage. Our objective was to estimate the association of complement behaviour with clinical manifestations, visceral injury and mortality in patients with SLE. Methods Complement determinations (C3 and C4 levels) were analysed in patients with SLE (fulfilling American College of Rh...