Measurement of eleven serum proteins by microparticle-enhanced nephelometric immunoassay.

Eleven proteins (immunoglobulins IgG, IgA, IgM, orosomucoid, alpha 1-antiproteinase, haptoglobin, ceruloplasmin, C-reactive protein, transferrin, prealbumin and alpha 2-macroglobulin) in human serum were quantitated by a new microparticle-enhanced nephelometric immunoassay. This is a one step competitive assay, based on the nephelometric measurement of light scattered by clusters of protein-coated microparticles specially synthesized for that use. Statistical evaluation (precision, recovery and method comparison) shows that the determination of serum proteins is reliable and accurate for wide ranges of concentration and that the method is quite adequate for strongly increased concentrations. This microparticle-enhanced nephelometric immunoassay appears to offer an alternative method for routine measurement of a great variety of serum proteins at high and intermediate concentrations, which are usually quantified by radial immunodiffusion or conventional immunonephelometry. On account of its sensitivity, it can also be used for the determination of relatively low concentrations of analytes.