Supplemental growth hormone increases the tumor cytotoxic activity of natural killer cells in healthy adults with normal growth hormone secretion.
Using double-blind, placebo-controlled procedures, the effects of methionyl-human growth hormone (met-hGH) on the tumor cytotoxic activity of natural killer (NK) cells were studied in seven healthy adults using a repeated measures experiment. Subjects were assigned at random to either a placebo (bacteriostatic water) treatment condition or a met-hGH (16.0 mg/wk of Protropin) treatment condition, then crossed-over to the alternative treatment. Treatments were delivered on alternate days (3 d/wk) for 6 weeks. Without bias from the met-hGH treatment, there was no evidence for GH hyposecretion as measured by the peak circulating GH response to exercise stimulation (14.1 +/- 3.1 ng/mL) or insulin-like growth factor (IGF-I) levels (0.82 +/- 0.09 U/mL). When compared with placebo, met-hGH induced a significant overall increase in the percent specific lysis (%SL) of K562 tumor target cells (placebo 22.2 +/- 1.7 v met-hGH 28.5 +/- 2.1 %SL; P = .008). NK activity was increased within the first week of treatment and this level was maintained throughout the remaining period of supplementation. There was a trend (P = .057) for the met-hGH-induced percent change in NK activity (NK%) to be inversely related to placebo IGF-I levels (r = -.761), while there were significant positive correlations between NK% and the met-hGH-induced percent changes in IGF-I (r = .727; P = .035), the fat-free mass (FFM)/fat mass (FM) ratio derived by hydrodensitometry (r = .792; P = .012), and the endogenous GH response to exercise (r = .469; P = .034).(ABSTRACT TRUNCATED AT 250 WORDS)
Crist
D M
DM
Department of Medicine, University of New Mexico School of Medicine, Albuquerque 87131.
Kraner
J C
JC
D000328:Adult; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D013006:Growth Hormone / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D019382:Human Growth Hormone; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009994:Osmolar Concentration; D010919:Placebos; D012016:Reference Values
D010919:Placebos; D019382:Human Growth Hormone; D013006:Growth Hormone