In the present work we studied the expression of membrane-bound Ig (MBIg) as well as receptors for IgG Fc and complement on nine human lymphoblastoid cell lines. When MBIg and receptors for IgG Fc were compared, four categories of cell lines could be distinguished: (a) cell lines having both MBIg and receptors for IgG Fc, (b) cell lines having MBIg but lacking receptors for IgG Fc, (c) cell lin...

Discrimination by the human alternative pathway between activating and nonactivating particles occurs after deposition of C3b by the continuous low-grade interaction of the alternative pathway components in biologic fluids and is dependent on the modulation by surface constituents of the interaction of bound C3b with the control proteins, beta 1H, and C3b inactivator (C3bINA). When heparin glyc...

Cleavage of C5 by C5 convertase is the last enzymatic step in the complement activation cascade leading to the formation of the cytolytic proteolytically activated form of C5 (C5b)-9 complex. In the present study, we examined the effect of the density of C3b (the proteolytically activated form of C3) on the function of the noncatalytic subunit of natural surface-bound forms of the enzyme. A com...

The secreted Staphylococcus aureus extracellular fibrinogen-binding protein (Efb) is a virulence factor that binds to both the complement component C3b and fibrinogen. Our laboratory previously reported that by binding to C3b, Efb inhibited complement activation and blocked opsonophagocytosis. We have now located the Efb binding domain in C3b to the C3d fragment and determined a disassociation ...

Polymer nanocomposites are being used more widely in a variety of industries. As the compatibilizer, Elvaloy-AC-3427 (EAC) was addition to Cloisite 30B (C3B) as reinforcement filler this research. For production Polyethylene/Cloisite 30B/Elvaloy AC-3427 nanomaterials, twin-screw extruder is employed. added Polyethylene matrix range 2%, 3%, 4%, and 5%. The mechanical thermal characteristics comp...

Glycoproteins C (gC) from herpes simplex virus type 1 (HSV-1) and HSV-2, gC-1 and gC-2, bind the human complement fragment C3b, although the two glycoproteins differ in their abilities to act as C3b receptors on infected cells and in their effects on the alternative complement pathway. Previously, we identified three regions of gC-2 (I, II, and III) which are important for C3b binding. In this ...

In this study the physiological role of properdin and the differential subunit composition of the solid phase enzymes of the pathway have been explored. Cell-bound C3 and C5 convertase differ in their C3b requirement. Apparently one molecule of C3b is sufficient to allow formation of C3 convertase (C3b,B), whereas two or more are required for generation of C5 convertase (C3bn,B). This conclusio...

Glycoprotein C (gC) of both herpes simplex virus type 1 (HSV-1) and HSV-2 interacts with complement C3b and protects the virus from complement-mediated neutralization. To study the mechanism by which gC modulates complement activation, we expressed both gC-1 and gC-2 in a baculovirus expression system. Baculovirus recombinants containing gC genes spanning the entire gC-1 sequence (gC-1-TMR) or ...

A glycoprotein from the membrane of human erythrocytes has been identified as a receptor for C3b (CR1). It promotes the dissociation of the alternative pathway C3 convertase C3b,Bb and the cleavage of C3b by C3b/C4b inactivator. We find that CR1 also inactivates the C3 and C5 convertases of the classical pathway. CR1 inhibits the consumption of C3 by C3 convertase EAC142 and enhances the decay ...

BACKGROUND AND OBJECTIVES Autoantibodies to complement C1q (anti-C1q) are associated with the diagnosis of lupus nephritis. In this study, we compare anti-C1q IgG with another complement autoantibody, anti-C3b IgG, as a biomarker of lupus nephritis and lupus nephritis flare. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Our investigation involved the Ohio SLE Study, a prospective observationa...