A sensitive microassay for the murine alternative complement pathway.

A microhemolytic assay for measurement of murine alternative complement pathway activity is described. The assay uses 51Cr release from neuraminidase-treated rabbit erythrocytes incubated with Mg2+ EGTA-chelated murine serum. Neuraminidase pretreatment of rabbit erythrocytes increases the sensitivity of the assay 8--10-fold, enable the use of small volumes of individual mouse sera. The assay affords a simple, sensitive and reproducible method for measuring murine alternative complement pathway activity. Significant differences were found between strains alternative complement pathway activity of serum from various inbred murine lines was measured.