Physicochemical Characterization of Direct Fluorescent Antibody Reagents

Abstract

When the data from performance and physicochemical studies of conjugates are combined for analysis, the performance data and specific titers show a direct relationship to the physicochemical data (Table 2). These reagents were prepared from the same lot of antiserum. The specific titers are very misleading without the accompanying data (Table 2). The protein concentrations range from 4 to 10 mg/ml, the F/P ratios from 10 to 30, and CASE shows gamma-globulin to constitute 30 to 100% of the protein. CASE also shows the gamma-globulin F/P ratio to be only 10 to 20. Using these data, we calculated the concentrations of the gamma-globulins and normalized their titers to 10 mg/ml. The value of good fractionation procedures for recovering gamma-globulin and the desirability of obtaining optimal F/P ratios are reflected in the adjusted titers. Physicochemical characterization of conjugates identifies superior and deficient reagents and frequently reveals the cause of inadequate performance. In this way it serves as a quide for improving reagent quality.