Laser nephelometry: development, clinical application, and future prospects

Plasma protein alpha 1-antitrypsin (alpha 1-AT) and the serum complement component C3 have been quantitated by a laser nephelometric technique. The correlation coefficient between the laser nephelometric and the RID methods was r = 0.87 for alpha 1-AT, and r = 0.80 for C3 in normal serum. The alpha 1-AT concentration determined by the laser method ranged from 161 to 393 mg/dl in normal plasma, whereas the serum C3 concentration in normal serum was found to be 76.5 +/- 21.9 mg/dl. In pathological plasma, higher-than-normal alpha 1-AT levels were found (mean = 300 +/- 105.2 mg/dl), and these elevated levels are consistent with an acute-phase response. These studies indicate that laser nephelometric methods can be conveniently employed and automated for rapid immuno-quantitation of plasma and serum proteins.