Measurement of beta 2-microglobulin in serum by a particle-enhanced nephelometric immunoassay

A particle-enhanced immunoassay of beta 2-microglobulin in serum is described. It is based on the agglutination of complexes formed between the serum beta 2-microglobulin and latex particles coated with F(ab')2 fragments of polyclonal anti-beta 2-microglobulin antibodies. The analytical range of the method is 0.50 to 16 mg/l; it can be extended by appropriate dilution to 0.12 to 80 mg/l with good precision (CV less than 5% over the whole range). The accuracy and the precision are confirmed by a good correlation with radioimmunoassay (n = 123, r = 0.993). No error due to antigen excess was observed, even up to 292 mg/l. The main advantages of the method are its simplicity, its low cost per test and its high sensitivity (final dilution of the sample at 1/1200) with no known interference. The calibration curve is stable for at least 2 weeks.