Detection of IFN-alpha produced in the presence of plasma gamma-globulin fraction proteins.

Interferon-alpha was detected in IFN pool produced by human leukocytes in the presence of gamma-globulin fraction proteins, copper and zinc cations, and metal-modified gamma-globulins. The cytokine appeared in culture medium at early terms (24 h) of incubation, is characterized by acid resistance, and is neutralized by antibodies to IFN-alpha. The content of IFN-alpha in supernatants of induced leukocytes reached 60-90 pg/ml and correlated with antiviral activity of the samples.

Induction of interferon production by conformation-modified proteins of plasma gamma-globulin fraction.

Plasma gamma-globulin fraction proteins, copper and zinc cations, and metal-modified gamma-globulins induce the production of IFN by human leukocytes. Binding of zinc cations attenuates the realization of the IFN-inducing effects of human serum gamma-globulin, while binding of copper cations potentiated this effect. Activity of IFN and the dynamics of its production correspond to those in response to phytohemagglutinin stimulation.

The Results of Mancini's test depend on the presence bound metal cations in the test protein.

Samples of human serum gamma-globulin with specifically bound copper or zinc cations were studied in Mancini's radial immunodiffusion test with human antibodies to IgG (H+L). The intensity of antibody binding to zinc-modified protein was 10-20% higher in comparison with the reference sample, while detection of gamma-globulin with bound copper by antibodies was 20-30% lower than in the corresponding reference sample. Comparison with the results of native gamma-globulin testing indicates limitations of Mancini's method as the quantitative assay for practical diagnosis, because under certain clinical conditions the traditional method can give over- and underestimated results.

Antigenic specificity of human serum gamma-globulin samples obtained under conditions of equimolar binding of copper and zinc cations.

Samples of human serum gamma-globulin modified by equimolar binding of copper and zinc cations were obtained using the method of molecular ultrafiltration. Conformation characteristics of the protein were studied by UV spectrophotometry. Immunochemical study included radial immunodiffusion test, direct and sandwich enzyme immunoassays.

Human serum gamma-globulin binds copper cations.

Binding of copper cations to human serum gamma-globulin was studied using molecular ultrafiltration. The content of free metal in the filtrate was evaluated by the reaction with sodium diethyldithiocarbamate. Conformation characteristics of the protein were evaluated by UV spectrophotometry.