IGF-I resistance in virus-transformed B-lymphocytes from African Efe Pygmies.
To investigate IGF-I resistance in African Efe Pygmies, we examined clonal responsiveness to IGF-I in Epstein-Barr virus-transformed B-lymphocytes from three Efe Pygmies and three American control subjects. The Efe B-lymphoblasts did not increase clonal responsiveness when incubated with IGF-I (as high as 250 micrograms/liter) in contrast to the control B-lymphoblasts which showed a bimodal dose-response with a maximal stimulation of 50% above baseline. The proliferative response of Efe B-lymphoblasts was similar to that of control B-lymphoblasts when incubated with another growth factor, phorbol 12-myristate 13-acetate, which does not activate the IGF-I receptor. These findings indicate that Efe Pygmy B-lymphoblasts are resistant to IGF-I as measured by in vitro clonal proliferation assays. Coupled with our previous report of IGF-I unresponsiveness in Efe Pygmy HTLV-II-transformed T-lymphocytes, these data suggest that IGF-I resistance is generalized and may play a central role in the etiology of short stature in this population.
Cortez
A B
AB
Department of Pediatrics, University of California at Los Angeles 90095, USA.
Van Dop
C
C
Bailey
R C
RC
Bersch
N
N
Scott
M
M
Golde
D W
DW
Geffner
M E
ME
D000328:Adult; D001402:B-Lymphocytes / Q000378:metabolism / Q000821:virology*; D044383:Black People; D001827:Body Height; D001835:Body Weight; D015023:Democratic Republic of the Congo / Q000208:ethnology; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism
D018972:Insulin-Like Growth Factor Binding Protein 3; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013972:Thyrotropin; D017526:Receptor, IGF Type 1