Growth hormone (GH) secretion from human lymphocytes is up-regulated by GH, but not affected by insulin-like growth factor-I.
Regulation of GH secretion from phytohemagglutinin (PHA)-stimulated lymphocytes was investigated in six normal subjects. Peripheral blood mononuclear cells were incubated with PHA (10 micrograms/mL) in the presence of various amounts of recombinant human GH (0-100 ng/L) and/or recombinant human insulin-like growth factor-I (0-1000 micrograms/L), and the secreted GH was measured by a highly sensitive enzyme immunoassay. PHA-stimulated lymphocytes secreted immunoreactive GH in all subjects (13.6 +/- 2.4 ng/L). Exogenous GH up-regulated the GH secretion in a dose-dependent manner, while IGF-I did not affect either basal GH secretion or the up-regulation by exogenous GH. These findings suggest a difference in the regulation of GH secretion between endocrine and immune systems.
Hattori
N
N
Department of Endocrinology, Kobe City General Hospital, Japan.
Shimomura
K
K
Ishihara
T
T
Moridera
K
K
Hino
M
M
Ikekubo
K
K
Kurahachi
H
H
D000328:Adult; D002478:Cells, Cultured; D005260:Female; D013006:Growth Hormone / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology
D010835:Phytohemagglutinins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone