A semi-automated microassay for complement activity.

A simple, automated microassay for the serum complement-dependent hemolytic activity is described here. In contrast to the traditional titration hemolysis assay, the new method depends on a single experimental step using a fixed volume of serum specimen and sheep erythrocytes. The assay is based on the change in light scattering properties of erythrocytes upon hemolysis. It relies on the spectrophotometric reading of microtiter well samples at 700 nm by using a microplate reader. The measured absorbance correlates proportionally with the extent of hemolysis. A good correlation between the results obtained using this technique and those obtained by the traditional CH50 titration method is observed. This simple procedure can be applied to the rapid, semi-quantitative diagnostic screening of complement activities of a large number of serum specimens.