Hemagglutination assay for human serum fibronectin.

A hemagglutination assay for human serum fibronectin (Fn) is described. The assay is based on the capacity of Fn to bind to gelatin. Purified and human serum Fn agglutinate chromic chloride treated sheep red cells coated with gelatin in a quantitative and reproducible manner. The lowest Fn concentration giving positive hemagglutination was found to be 7 micrograms/ml, a sensitivity making it suitable for measurement of Fn in both normal and pathologic sera. The assay is simple and rapid and does not require specialized equipment.

Fibronectin and lymphocyte blast transformation.

Purified human plasma fibronectin (Fn) added to human peripheral blood leukocytes culture, from 22 healthy blood donors, phytohemagglutinin (PHA) stimulated, enhanced mitogen action in blast transformation. Daily measurement (between 1-6 days) of Fn concentration in culture supernatants incubated with PHA, Fn and associated doses of Fn and PHA, pointed out a significantly increased Fn concentration, on the fourth day, in the cultures incubated with Fn and PHA. On the fourth day of PHA stimulated cultures were found, the increased Fn concentration, as well as the maximum blast transformation. Our data suggest that Fn, synthetized by activated macrophage in intercellular cooperation processes is released in culture supernatants with a maximum on the fourth day. These results show the possible role of Fn to influence blast transformation enhancement of mitogen action.

Anti-albumin antibodies in chronic liver diseases: diagnostic significance of these antibodies in patients with conventional or immunosuppressive therapy.

The two categories of anti-albumin antibodies (AAA), namely precipitins (AA-P) and agglutinins (AA-Aggl), were investigated in 260 patients with morphologically diagnosed chronic liver diseases (CLD). A parallelism was observed between AA-P titre and the severity of chronic hepatitis as revealed by clinical diagnosis. Thus, significant differences in AA-P titre were noticed between chronic persistent hepatitis (CPH) and chronic aggressive hepatitis (CAH) and between CAH and liver cirrhosis (LC). No correlation was found between AA-P positivity and either HBsAg presence or disease activity, maximum AA-P values being registered in decompensated, inactive LC. AA-P positivity was found associated with a higher degree of liver cell dysfunction. In every category of CLD a striking association was also observed between AA-P positivity and raised serum aspartate transaminase and bilirubin levels, thus suggesting a common pathogenic substrate, namely liver cell membrane damage. These correlations were also observed after immunosuppressive therapy which would argue for the maintenance of AA-P diagnostic value. AA-Aggl showed raised incidences and titres in CAH patients, the values decreasing in LC. Therefore, the main diagnostic value is attributed to AA-P.

Immunochemical characterization of anti-albumin antibodies in liver diseases.

Anti-albumin antibodies (AAA) were isolated from sera of hepatic patients and normal individuals by affinity chromatography on insolubilized glutaraldehyde-treated human albumin. Anti-albumin antibodies were found to belong to IgG and IgM classes in both normal and hepatic patients. The normal level of AAA increased in pathologic conditions, the increase recorded for IgM AAA being higher than that for IgG AAA. The dissociation rate of AAA from the radiolabeled antigen in normal and hepatic sera showed that the affinity of AAA was higher in normal sera than in sera of patients with chronic liver disease and acute viral hepatitis. Anti-albumin antibodies were fractionated into two populations (AAA1 and AAA2) by a two-step chromatographic procedure. AAA1 and AAA2 were found different as regards their affinity for the antigen; specifically, AAA1 affinity was higher than that of AAA2. The other difference between AAA1 and AAA2 might stand in their specificity for the haptenic and structural determinants present in the glutaraldehyde-treated albumin.

Fibronectin and phagocytosis in acute and chronic infections.

Serum fibronectin (Fn) level and phagocytosis function were investigated during acute and chronic infections. Serum Fn concentration was significantly decreased in septic patients (mean +/- ES, 80 +/- 12 micrograms/ml, p less than 0.001) and was increased in chronic bronchitis patients (575 +/- 18 micrograms/ml, p less than 0.001) as compared to the controls. The phagocytosis index was decreased in septicaemia and not significantly changed in chronic bronchitis. Phagocytosis dysfunction was associated to a low serum Fn level in acute infections. Phagocytosis was stimulated in vitro, by purified Fn. Serum Fn concentration reflects the reticuloendothelial function and could be a marker of infection together with other parameters.

Plasma fibronectin level in patients with connective tissue diseases.

The level of plasma fibronectin (Fn) was studied in 40 patients with connective tissue diseases. Fn concentration was found increased in patients with rheumatoid arthritis (mean +/- SE, 560 +/- 30 micrograms/ml, p less than 0.01) decreased in patients with mixed connective tissue disease (337 +/- 12 micrograms/ml, p less than 0.05) and was not significantly different from controls in systemic lupus erythematosus, scleroderma, polymyositis. The value of plasma Fn level was found increased in active diseases and decreased in the cases, with presence of cryoprecipitates. The factors which might influence the level of plasma Fn and the possibility of using the changes of Fn concentration in the estimation of the evolution of connective tissue diseases are discussed.

Serial analysis of fibronectin concentration in sera from septic patients.

Serum fibronectin (Fn) level was serially determined in nineteen septic patients. Fn concentration was found significantly decreased in septic patients (mean +/- SE, 120 +/- 11 micrograms/ml) as compared to the control (205 +/- 11 micrograms/ml). The decrease of Fn was correlated with the severity of sepsis; it was persistent and more important in severe septic cases. The lowest Fn concentration was found in nonsurviving patients (78 +/- 18 micrograms/ml). Serum Fn level may reflect the degree of organ failure and predict the evolution of sepsis.