Lectin affinity electrophoresis of alkaline phosphatase for the differentiation of bone and hepatobiliary disease

An affinity electrophoresis procedure is described for the separation and quantification of the bone- and liver-derived fractions of alkaline phosphatase in plasma. Separation is carried out on cellulose acetate membrane pre-soaked with buffer containing wheat germ lectin. The electrophoretic mobility of the bone enzyme is preferentially retarded by the lectin and this fraction is well separated from the liver fraction. After separation, enzyme activity is demonstrated by staining using an indigogenic alkaline phosphatase substrate incorporated in agar gel, and the stained fractions quantified by densitometry. The procedure has low imprecision, good linearity, and the activities of the bone and liver fractions correlate well with values obtained using nonelectrophoretic quantification methods. The procedure is especially suitable for use in the diagnostic laboratory.