UNLABELLED Natural killer (NK) cells and the complement system play critical roles in the first line of defense against pathogens. The synthesis of complement components C4 and C3 is transcriptionally downregulated by hepatitis C virus (HCV) core and NS5A proteins, and this negative regulation is apparent in chronically HCV-infected patients. In this study, we have examined the potential contri...

This report describes a patient with hereditary angioedema (HAE) in whom complement C4 values were consistently normal. There was a family history of HAE, for which the patient had previously been screened, but in view of her normal C4 values she was deemed unaffected. However, at 10 years of age she presented with an eight month history of episodes of swelling affecting her hands and recurrent...

The complement system is an important humoral defense mechanism that plays a relevant role against microbial agents, inflammatory response control, and immunocomplex clearance. Classical complement pathway activation is antibody-dependent. The C4 component participates in the initial step of activation, and C4 expression is determined by 2 pairs of allotypes: C4A and C4B. Deficiencies in C4 all...

PURPOSE The complement system is part of the innate defense system of the body, and it contributes to inflammatory conditions. The current study examined tears for the presence of complement components, the activity of the components, and the presence of regulatory components. METHODS The significance of a functional complement system in tears was examined in four ways. First, the presence an...

The biochemical and physiological characteristics of C4 photosynthesis have been researched and clarified in detail. We now know that the differentiation of two cell types, mesophyll cells (MC) and bundle sheath cells (BSC), is required for efficient C4 photosynthesis. Thus, the leaves of C4 plants have more complicated structural and functional features than those of C3 plants (Hatch, 1999; Ka...

The role of Complement factors in the pathogenesis of psychiatric disorders is enormous, but the data on levels and functions of complement factors in patients with schizophrenia are scanty and conflicting. To address this issue, levels of Complement regulators (C1 inhibitor and C3 activator) and complement factors (C1q, C3c, C4 and C5) were determined in the serum of newly diagnosed drug free ...

Levels of C4d, a fragment of C4 generated during activation of the classical complement pathway, were measured in the plasma of 48 patients with systemic lupus erythematosus, 11 with inactive (group 1), 23 with mildly active (group 2), 14 with moderately/severely active disease (group 3), and 30 healthy subjects. Levels of C3d, C4, and C3 were also measured and the C4d/C4 and C3d/C3 ratios calc...