ELISA for Human Tissue-Unspecific (liver/bone/kidney) Alkaline Phosphatase

Abstract

We established an enzyme-linked immunosorbent assay for tissue-unspecific alkaline phosphatase using specific monoclonal antibodies prepared against liver alkaline phosphatase. The concentration of serum tissue-unspecific alkaline phosphatase was determined in the range of 1.5 to 100 ng/ml. The coefficients of variation in the between-day assay and the within-day assay were 3.2-6.9% and 6.8-7.9%, respectively. The recovery of tissue-unspecific alkaline phosphatase from various serum samples was 94.1%-95.8%. This method can be clinically applied. In serum of a patient with infantile hypophosphatasia which is one of six types of hypophosphatasia that is deficient in tissue-unspecific alkaline phosphatase, both the concentration and the activity of serum tissue-unspecific alkaline phosphatase were lower than those in the sera of healthy individuals. This suggests that the lower activity of tissue-unspecific alkaline phosphatase in this patient with infantile hypophosphatasia is due to the lower expression of tissue-unspecific alkaline phosphatase, the production of the non-immunoreactive abnormal protein of tissue-unspecific alkaline phosphatase and/or less of it being transported from the cell membrane to the circulation.