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Study of six antisera used for the immunonephelometric assay of human IgG
F Pontet1, M C Diemert, M Pressac
1Laboratoire Central de Biochimie, Hôpital Lariboisière, Paris.
The composition and performance of six commercial antisera for the immunonephelometric assay of IgG were studied. The analysis of the protein content of these reagents revealed significant differences in composition: the total protein contents ranged from 41 to over 130 g/l and gamma-globulins were twice to thirteen times higher than in a normal serum of the species. The antibodies found in these reagents were mostly IgG, with traces of IgM, and no IgA. Precipitation curves yielded by these antisera with a standard nephelometer showed a great diversity of performance. The very different shapes, the span of antigen concentrations and antibody dilutions necessary to obtain comparable quantities of precipitates further demonstrated the wide differences between these reagents. A method previously proposed by other authors was found to be inadequate. The failure of this method is attributed to the different conditions for the antigen-antibody reaction, as determined by the instrumentation used. It is concluded that the fundamental and classical criteria for testing antisera remain valid: specificity and the study of the precipitation curve to define the quantitative limits of the reaction. A simple universal method is inapplicable.
The composition and performance of six commercial antisera for the immunonephelometric assay of IgG were studied. The analysis of the protein content of these reagents revealed significant differences in composition: the total protein contents ranged from 41 to over 130 g/l and gamma-globulins were twice to thirteen times higher than in a normal serum of the species. The antibodies found in these reagents were mostly IgG, with traces of IgM, and no IgA. Precipitation curves yielded by these antisera with a standard nephelometer showed a great diversity of performance. The very different shapes, the span of antigen concentrations and antibody dilutions necessary to obtain comparable quantities of precipitates further demonstrated the wide differences between these reagents. A method previously proposed by other authors was found to be inadequate. The failure of this method is attributed to the different conditions for the antigen-antibody reaction, as determined by the instrumentation used. It is concluded that the fundamental and classical criteria for testing antisera remain valid: specificity and the study of the precipitation curve to define the quantitative limits of the reaction. A simple universal method is inapplicable.