Insulin-like growth factor-I unresponsiveness in an Efe Pygmy.
The cause of short stature in African Pygmies is unknown, but some evidence suggests that they are GH resistant. Since IGF-I mediates many actions of GH, we sought to determine if Pygmy tissue is responsive to IGF-I. We established HTLV-II-transformed cell lines from 1 Efe Pygmy, 1 African control, and 3 American controls, and quantified in vitro colony formation in response to IGF-I, GH, and insulin, and assessed IGF-I receptor binding. The Pygmy T-cell line showed no clonal responsiveness following stimulation with physiologic concentrations of IGF-I or any concentration of GH, but responded normally to insulin. IGF-I binding studies showed no binding to the Pygmy T-cell line with normal binding to control cells. The primary abnormality in this Pygmy T-cell line is IGF-I resistance at the receptor level with secondary GH resistance.
Geffner
M E
ME
Department of Pediatrics, University of California, Los Angeles 90024.
Bailey
R C
RC
Bersch
N
N
Vera
J C
JC
Golde
D W
DW
D000328:Adult; D044383:Black People; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D015023:Democratic Republic of the Congo; D005006:Ethnicity; D013006:Growth Hormone / Q000494:pharmacology*; D015367:Human T-lymphotropic virus 2 / Q000235:genetics; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism
D007328:Insulin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D017526:Receptor, IGF Type 1