BACKGROUND Chronic obstructive pulmonary disease and emphysema develops in 15% of ex-smokers despite sustained quitting, while 10% are free of emphysema or severe lung obstruction. The cause of the incapacity of the immune system to clear the inflammation in the first group remains unclear. METHODS AND FINDINGS We searched genes that were protecting ex-smokers without emphysema, using microar...

The bacterium Francisella tularensis (Ft) is a potential weapon of bioterrorism when aerosolized. Macrophage infection is necessary for disease progression and efficient phagocytosis by human macrophages requires serum opsonization by complement. Microbial complement activation leads to surface deposition of a highly regulated protein complex resulting in opsonization or membrane lysis. The nat...

UNLABELLED Complement is an innate immune system that most animal viruses must face during natural infections. Given that replication and dissemination of the highly pathogenic Nipah virus (NiV) include exposure to environments rich in complement factors, we tested the in vitro sensitivity of NiV to complement-mediated neutralization. Here we show that NiV was completely resistant to in vitro n...

The plasma membranes of phagocytic leukocytes have receptors for the Fc portion of IgG (1-6) and for a cleavage product of the third component of complement, C3 (3, 4, 6-8). These receptors are distinct from one another (1-3) and serve different functions in promoting the interaction of phagocytic cells with immunologically coated particles and soluble material in the cells' environment (6-10)....

Complement factor H (CFH) is the major regulator of the central complement protein C3b in the alternative pathway of complement activation. A molecular view of the CFH interaction with native heparan sulfate (HS) is central for understanding the mechanism of how surface-bound CFH interacts with C3b bound to host cell surfaces. HS is composed of sulfated heparin-like S-regions that alternate wit...

The susceptibility of adult sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), to five local Syrian isolates of Heterorhabditis bacteriophora, Steinernema riobravae Texas, S. carpocapsae C3B, and H. bacteriophora 8-14 strains was evaluated under laboratory conditions. Concentrations of 50, 100, 200, and 400 nematodes per adult were bioassayed; for each nematode concentration, f...

A human myeloid cell subline, P39 +, is found to be a target for human complement (C) via the alternative pathway and to allow the deposition of multiple C3 fragments on its membranes, though expressing the complement regulatory proteins decay-accelerating factor and membrane cofactor protein. The parent cell line, P39-, which is phenotypically similar to the P39 + subline, does not allow the d...

Complementary DNA clones encoding the NH2-terminal region of human CR1 have been isolated and sequenced. The deduced complete amino acid sequence of the F allotype of human CR1 contains 2,039 residues, including a 41-residue signal peptide, an extracellular domain of 1,930 residues, a 25-amino acid transmembrane domain, and a 43-amino acid cytoplasmic region. The extracellular domain is compose...

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...

BACKGROUND Natural IgM containing anti-Gal antibodies initiates classic pathway complement activation in xenotransplantation. However, in ischemia-reperfusion injury, IgM also induces lectin pathway activation. The present study was therefore focused on lectin pathway as well as interaction of IgM and mannose-binding lectin (MBL) in pig-to-human xenotransplantation models. METHODS Activation ...