Detection of ALP-linked immunoglobulin by electrosyneresis

Abstract

A simple and sensitive method is presented for detection of alkaline phosphatase (ALP)-linked immunoglobulin in human serum. This method is based on the empirical observation that ALP activity of ALP-linked IgG has been present on the anode side of IgG immunoprecipitin arc by immunoelectrophoresis.
The procedure is as follows; 3μl each of the serum sample and antiserum are applied on the commercial agarose gel film, and then electrosyneresis is carried out. After washing out free ALP in the gel film with saline solution containing 1.75mM MgCl₂, the film is incubated with ALP staining reagents. ALP-linked immunoglobulin is detected by ALP activity on the immunoprecipitin line.
By this method, ALP-linked immunoglobulin was detectable even after ALP VI had disappeared by isoenzyme analysis. It was superior to conventional methods (enzyme-immunoelectrophoresis and enzyme-immunoprecipitin reaction in free liquid media) in sensitivity and simplicity of procedure. The present mothod was proved to be the most useful for the detection of ALP-linked immunoglobulin, especially for the screening test.