Journal of Clinical Endocrinology & Metabolism, Vol 64, 1042-1046, Copyright © 1987 by Endocrine Society

ARTICLES

Tissues of the Laron dwarf are sensitive to insulin-like growth factor I but not to growth hormone

ME Geffner, DW Golde, BM Lippe, SA Kaplan, N Bersch and CH Li

Tissues from patients with Laron dwarfism are resistant to the actions of endogenous or exogenous GH. As a result, insulin-like growth factor I (IGF-I) levels are low, possibly contributing to the severe growth deficiency that occurs in patients with this syndrome. In this study, we found that erythroid progenitor cells and permanently transformed T- cell lines from two patients with Laron dwarfism responded in vitro to added IGF-I in concentrations ranging between 1-10 ng/mL despite no stimulatory response to added GH in concentrations of up to 500 ng/mL. Normal or near-normal responsiveness to insulin was also demonstrated. The persistence of GH resistance in the cultured T-cell lines confirms the primary genetic nature of the defect in Laron dwarfism. The preservation of in vitro growth responsiveness to IGF-I in hematopoietic tissue from the Laron dwarfs suggests that affected individuals are sensitive to this factor and may respond to it in vivo.

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