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Results for “Complement C9”

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PubMed1990

Involvement of granule proteins in T-cell-mediated cytolysis.

Cytolytic T lymphocytes (CTL) and large granular lymphocytes contain dense cytoplasmic granules which, when isolated, are lytic for a variety of target cells. Granule proteins are released from the effector cell upon target cell interaction, further suggesting that they play a role in the cytolytic mechanism. Major proteins in CTL granules are a family of serine esterases (granzymes) and a pore-forming protein called perforin (cytolysin). Despite structural similarities between functionally conserved regions of perforin and the ninth component of complement (C9), these two lytic molecules are clearly distinct in their mode of target cell recognition. Perforin, unlike C9, is not dependent on a protein receptor molecule but binds to the target cell membrane via phosphorylcholine in a Ca2(+)-dependent manner. Here, we discuss the stimulus-secretion model for T-cell-mediated cytotoxicity with respect to our current understanding of perforin and the granzyme proteases.

Animals↗
PubMed1989

Decay accelerating factor regulates complement activation on glomerular epithelial cells.

Epithelial cells of the glomerular capillary are the site of C5b-9 mediated injury in rat membranous nephropathy. We investigated the regulation of C activation by cultured glomerular epithelial cells (GEC). Rat and human GEC were more resistant to C injury by homologous C than heterologous C. In human GEC homologous C cytotoxicity was enhanced by antiserum to decay accelerating factor (DAF) indicating that homologous C activation was, at least in part, restricted by membrane DAF. Anti-DAF immunoprecipitated a 67-kDa protein from human glomeruli. In rat GEC, pronase and phosphatidylinositol-specific phospholipase C (which are known to inactivate human DAF) enhanced cytotoxicity by homologous C. Thus, DAF is present on human GEC in culture and in human kidney glomeruli, and a DAF-like protein is present on cultured rat GEC. These proteins regulate C activation in vitro and may play a role in controlling C activation on GEC in vivo.

Animals↗
PubMedDate not supplied

[Complement system].

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Age Factors↗
PubMed1986

Effects of smoking on inflammatory mediators and their relationship to pulmonary dysfunction.

Study populations of 170 male smokers and 170 age- and sex-matched nonsmokers were used to determine the effects of cigarette smoking on pulmonary function, peripheral blood leukocytes and phase reactive proteins. Further, the interrelationships between these parameters were sought. Consistent with their young age (mean 37 years) and relatively brief smoking history (mean 24 pack-years), the smokers had a significant, yet modest, impairment of pulmonary function as measured by both forced expiratory spirometry and the single breath nitrogen/closing volume test. Smokers exhibited a significant elevation in total peripheral blood leukocytes which was attributable to increases in neutrophils, lymphocytes, monocytes and eosinophils. Similarly, significant increases in the "phase reactive" proteins [i.e., the ninth component of complement (C9), ceruloplasmin and alpha 1-protease inhibitor (alpha 1-PI)] were also observed in smokers. Increases in total leukocytes, neutrophils, C9 and alpha 1-PI were significantly associated with present and cumulative cigarette consumption, blood levels of smoke constituents/metabolites (i.e., carboxyhemoglobin, nicotine and cotinine) and impaired pulmonary function (i.e., FEV1 and FVC). However, duration of smoking (years smoked) and pack-years smoking history were the best predictors of elevations in inflammatory mediators and pulmonary dysfunction. These data support the hypotheses that: a low grade inflammatory reaction is induced in smokers and is dependent upon a dose-related exposure to smoke; and the smoking-induced changes in inflammatory mediators are associated with the observed pulmonary dysfunction.

Adult↗
PubMedDate not supplied

Myasthenia gravis: demonstration of membrane attack complex in muscle end-plates.

The membrane attack complex (MAC) assembles from C5b-9 complement components and has neoantigenic properties. Antihuman-MAC rabbit immunserum was applied in order to localize the MAC in myasthenic muscles. Using the indirect immunoperoxidase method MAC was demonstrated at the motor end-plates in eleven myasthenic patients who underwent thymectomy. This result provides direct evidence of antibody-dependent complement-mediated injury of acetylcholine receptors in myasthenia gravis.

Adolescent↗
PubMed1979

Interactions of complement with the red-cell membrane.

Interactions of the complement components with the red-cell membrane are, as delineated, many and complex. Much is known about the nature of the complement components that take part in these interactions, but relatively little is known about the membrane or the components of the membrane with which they interact. Such understanding will be essential if we are to be able to explain the great resistance to complement lysis shown by normal red cells or the abnormalities that result in increased or decreased interacition of complement with abnormal red cells.

Antibodies↗
PubMed1985

Immunofluorescence studies of cardiac valves in infective endocarditis.

Mitral and aortic valves removed at emergency cardiac surgery from a patient with infective endocarditis caused by Streptococcus viridans were studied by immunofluorescence to ascertain the extent and pattern of various immune reactants within the large valvular vegetations. Heavy intravalvular deposits of IgG as well as bacterial antigen were present. Much more focal interstitial IgM and C3 deposits were noted within vegetations and valve substance. Diffuse endocardial and subendocardial deposition of C5b-C9 and C9 complement neoantigens was present. Direct staining of valvular tissues and vegetations for rheumatoid factor showed extensive interstitial tissue deposition. These findings emphasize the large amounts of immune reactants and constituents of immune complexes present in valves and vegetations of patients with infective endocarditis.

Adult↗
PubMed1979

Serum complement concentrations, nutritional status and the outcome of measles and measles pneumonia.

A prospective study of children with measles has shown a significant association between malnutrition and a poor prognosis. Levels of a number of complement components bore no relationship to the severity of the disease or to its prognosis. Some of the children with acute measles had depressed serum concentrations of factor D, Clq or C3, but complement deficiency does not appear to be implicated in the heightened susceptibility to secondary bacterial and viral infection so commonly found after acute measles.

Body Weight↗