Increased susceptibility to infection in children with congenital deficiency of factor I.
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Bacterial Infections↗
Biomedical subjects
D Ponard
Publications and source records attributed to D Ponard.
Functionally active complement proteins C6 and C7 detected in C6- and C7-deficient individuals.
Two sensitive sandwich ELISAs based on monoclonal antibodies directed to native C6 and C7 allowed the detection and quantitation of these complement proteins in 20 out of 37 serum samples from individuals who had previously been classified as deficient in these proteins as assessed by immunochemical and/or functional assays. Furthermore, serum from four C6-deficient and one combined C6-/C7-deficient individual showed an increase in the terminal complement complex (TCC) and a decrease in native C6 and C7 after complement activation as assayed by specific ELISAs. Despite their (incomplete) deficiencies, these individuals therefore possess functionally active terminal complement proteins with respect to their ability to generate the TCC. As these individuals have no history of a susceptibility to neisserial infections, even low concentrations of functionally active C6 and C7 may provide sufficient protection against those micro-organisms whose destruction requires TCC formation.
Antibodies, Monoclonal↗
Reactivity patterns of anti-phospholipid antibodies in systemic lupus erythematosus sera in relation to erythrocyte binding and complement activation.
We studied 51 sera from patients with systemic lupus erythematosus to determine the relationship of their anti-phospholipid activity to their anti-erythrocyte and complement activation properties. Forty-nine per cent of the sera had anti-phospholipid activity as demonstrated by ELISA using a panel of anionic phospholipids, and most of these also bound to neutral phospholipids, albeit to a lesser extent. A cellular radioimmunoassay was used for the detection of immunoglobulin and C3 binding to normal erythrocytes (intact, enzyme-treated or glutaraldehyde-fixed) following incubation with patient sera. The levels of IgG anti-phospholipid correlated with hypocomplementaemia and with immunoglobulin binding (paralleled by a deposition of C3 fragments) to the three types of erythrocytes, although most strongly to fixed cells. Immunoglobulin binding to intact erythrocytes correlated primarily with reactivity against neutral phospholipids. The specificity for phospholipid epitopes of immunoglobulin adsorbed onto erythrocytes was confirmed by acid elution followed by testing in ELISA. These data suggest that some anti-phospholipid antibody subsets may bind to erythrocytes in vivo, thus accounting for the observed association of these antibodies with positive direct antiglobulin tests.
Antibodies, Antinuclear↗
[Evaluation of the bactericidal effect of the membrane attack complex of serum complement].
The bactericidal activity of serum complement and particularly of the membrane attack complex (MAC-C5b-C9) was studied on E. coli C600 with a simple functional test. The test evaluates the in vitro kinetics of the bactericidal effect and the subsequent counting of surviving germs. Homozygous deficiency of a particular membrane attack complex protein was easily detected from a total loss of bactericidal activity. These results were confirmed on Neisseriae meningitidis A and C, but in this case a more complex protocol was required. Deficits of proteins of the membrane attack complex sequence of complement are often found in sera of patients suffering from recurrent Neisseriae infections. This simple test, adapted to family studies, appears, thus, as a valuable basis for a detection of relatives at risk.
Blood Bactericidal Activity↗
A sensitive method to assay blood complement C1- inhibitor activity.
Hereditary angioneurotic edema results from deficiency of complement protein C1- inhibitor. Using a new spectrophotometric assay for C1-s esterase activity on the N-alpha-benzoyl-L-arginine ethyl ester, we describe a routinely available method for quantifying low C1- Inhibitor functional activities in EDTA-treated plasma of hereditary angioneurotic edema patients. C1- Inhibitor activity is deduced from the residual esterase activity of C1-s incubated with 20-80 microliters plasma samples. Arbitrary units (volume of sample inhibiting 50% of C1-s activity) were used to express C1- Inhibitor normal activity which was estimated as 22,500 +/- 5,000 (SD) U/l in 45 healthy individuals. The correlation with C1- Inhibitor antigen in these healthy individuals and 89 patients with varying concentrations of C1 Inhibitor ranging from 0.05-1.05 g/l was r = 0.91. Levels down to 2,000 U/l could be estimated. Specific inhibitory activity is an absolute requirement to distinguish between type I and type II hereditary angioneurotic edema.
Complement C1 Inactivator Proteins↗
Diagnosis of malaria in non-endemic countries by the ParaSight-F test.
QBC, examination of thin blood smears, and Parasight-F were performed for every case of malaria suspected between May 1997 and December 1998. Data from 310 patients were reported. Fifty had malaria infection diagnosed by QBC and thin blood film, among whom 39 had Plasmodium falciparum infection. Three of these 39 were negative with the Parasight-F test. Eleven patients had a positive ParaSight-F test but microscopic diagnosis methods were negative. Interpretation of these 11 positive ParaSight-F results is proposed to depend on clinical criteria.
Animals↗