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Immunochemical studies with natural gastrin

University of British Columbia

The antral hormone gastrin has generally been regarded as a non antigenic molecule necessitating its conjugation with a large "carrier” to be an effective inducer of antibody. Such conjugation has normally taken the form of covalent binding to a highly antigenic molecule or ionic binding to an inert particle. Alternatively, some success has been achieved by the injection of impure antral extracts. This report describes four approaches to the problem of the induction of antibodies specific for gastrin. Initially, natural hog gastrin was obtained after the procedure of Gregory and Tracy (1964). The pure active hormone was modified by alkaline hydrolysis to liberate an N-terminal amino group for covalent conjugation. The modified gastrin, however, was not specifically identified or isolated in quantity. Consequently, pure and impure antral extracts, hemocyanin-bound synthetic human gastrin and latex-bound gastrin were applied to a variety of animals. Passive hemagglutination tests in ducks revealed titres of 400 to 1600 to both the pure and impure extracts but a series of four injections of pure gastrin into an antrectomized rabbit failed to raise detectable antibody. Injections of 3 mg. of SHG bound to hemocyanin was unsuccessful; antibody titre to the carrier molecule was high but no specificity appeared to be directed to the synthetic hapten. The immunization of chickens with latex-bound natural gastrin was more fruitful. Although a number of precipitin tests established the presence of antibodies to gastrin, it was apparent that the assay was inadequate as a sensitive test for the bivalent antigen. Furthermore, the antibody titre was not sufficiently high to be successfully applied to a radioimmunoassay.

Text

2011-05-18

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http://hdl.handle.net/2429/34667

Physiology

University of British Columbia

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