Spectroturbidimetric determination of the sizes of poly(ethylene glycol)-induced insoluble immune complex particles

摘要

A spectroturbidimetric method adaptable to routine clinical practice is proposed for estimating the sizes of insoluble immune complex particles in poly(ethylene glycol) (PEG)-treated blood serum. In order to determine average particle diameter d from wavelength exponent w (the exponent in the power approximation of turbidity spectra), calibration is performed relative to polystyrene latexes, d (nm) = exp(8.2-0.9w). To optimize the method, the influence of PEG concentration and antigen/antibody ratio on the average sizes of formed particles is studied by the example of a model antigen (tetanic toxoid)-antibody (human antitoxoid γ-globulin) system. The optimized procedure is used to analyze human blood serum. It is shown that, in the presence of 3% PEG, the average particle sizes and volumes of the insoluble immune complexes are significantly different in healthy individuals and patients with rheumatoid arthritis. These differences are in significant correlation with the rheumatoid factor level determined in sera through the standard latex agglutination test.