Limitations of conventional laser nephelometry for the measurement of beta 2-microglobulin, lysozyme, alpha 1 fetoprotein and myoglobin in serum and urine.

We have tested some assay procedures for the measurement of beta 2-microglobulin, lysozyme, alpha 1-fetoprotein and myoglobin in serum and/or urine with the use of a manual Behring laser nephelometer. The assay working ranges were: beta 2-microglobulin: 0.0038-0.038 g/L; lysozyme: 0.005-0.325 g/L. We have studied the effect of different antiserum dilution ratios and of different concentrations of polyethylene glycol 6000 on the calibration curves. The best standard curves were obtained with the use of the following antiserum dilutions: anti-beta 2-microglobulin: 1:3 with saline, 40 g/L PEG; anti-lysozyme: 1:5 with saline, 40 g/L PEG; anti alpha 1-fetoprotein: concentrated; anti-myoglobin: concentrated with added 40 g/L PEG. In the case of beta 2-microglobulin and lysozyme, laser nephelometry, could be a fast and simple procedure if a 10 times increase in sensitivity can be achieved. For the measurement of alpha 1-fetoprotein and myoglobin, the sensitivity of laser nephelometry was disappointing when compared to those reported for radioimmunoassay and enzyme immunoassay.