RESUMO
PURPOSE: Currently the most widely used method of measuring IgG concentration is the method employing ELISA. This method has an advantage to detect smaller quantities than other standard methods, but in certain cases, consistent results cannot be obtained, thus impairing reliable data analysis. In this study, we attempt to determine the advantages in data analysis offered by the new method developed by Binding Site Ltd. (England) that employs a nephelometry. METHODS: 20 healthy subjects were studied from each of the following age groups : neonates, 1-4 months old, 5-10 months old, 11-24 months old, and 2-5 years old children. Serum IgG and IgG subclass concentrations were measured by nephelometry (Gehring Nephelometer Analyzer II, Germany) using Human IgG subclass, Liquid reagents BNII kit (Binding Site Ltd., England). RESULTS: 1) The r values for the standard curves of IgG, IgG1, IgG2, IgG3, IgG4 concentrations were 0.991, 0.997, 0.980, 0.973, 0.997, respectively. 2) IgG, IgG3, and IgG4 concentrations were lowest at the age of 5-10 months and increased to normal adult levels at 2-5 years of age. 3) IgG1 and IgG2 were lowest at the age of 1-4 months and increased to normal adult levels at 2-5 years of age. CONCLUSION: The method employing nephelometry for measuring serum IgG & IgG subclasses concentration is not as sensitive as ELISA in detecting the lower concentrations. However, our studies indicate that it presents the advantage of better quality control in measuring values in the average range.