| Research Abstract |
Recently it has been reported that serum GH binding protein (GHBP) is a extracellular hormone binding domain of the GH receptor. Therefore, the measurement of serum GHBP may be useful to evaluate GH receptor in vivo. At present, gel filtration method is used for measurement of serum GHBP, but by this method multiple samples could not be measured simultaneously. We have developed a simple method for measurement of serum GHBP using anti-GH receptor antibody. Binding of ^<125>I-hGH to human serum GHBP was immunoprecipitated with monoclonal anti-GH receptor antibody (GHRAB : * 263 ; AGEN Biomedical Ltd, QLD, Australia) that did not inhibit hGH binding to human serum GHBP. Serum GHBP in various clinical conditions was measured by this method, and the results were expressed'as percent specific binding relative to an adult reference serum. Serum GHBP values in normal adult males, normal adult females, patients with GH deficiency and patients with acromegaly were 87.5<plus-minus>9.7, 74.3<plus-minus>5.3, 106.3<plus-minus>5.2, and 35.4<plus-minus>4.4%, respectively, suggesting that GHBP is regulated by endogenous GH. Scatchard analysis of the bindings, carried out with correction made for endogenous serum GH, revealed that changes of the binding were mainly due to the changes of binding capacity. Furthermore, the serum GHBP values in patients with liver cirrhosis and poor nutritional conditions, and in some short children and those in late pregnant women and patients with ossification of the posterior longitudinal ligament (OPLL) were elevated From the above data, we conclude that this method could be practical to evaluate GH receptor in various clinical conditio
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