Production of interleukin-1-alpha and interleukin-2 by mononuclear cells in healthy adults in relation to different experimental conditions and to the presence of growth hormone

Several reports support the view that the growth hormone (GH) possesses a number of important immunomodulatory properties. This study was undertaken to determine in vitro the role of the GH on interleukin (IL) production. Cultures of blood peripheral lymphocytes obtained from human normal adults were performed in RPMI medium in the presence or absence of phytohemagglutinin (PHA), heated normal serum (NHS) 1% and GH 12.5-500 microgram/l. After incubation from 15 h to 4 days at 37 degrees C in a humidified atmosphere containing 5% CO2, cells were discarded and the supernatants were tested for their contents of IL-1 alpha and IL-2 measured using the Amersham radioimmunoassay system. The results of these in vitro experiments show that: (1) the bulk cultures from peripheral lymphocytes are suitable to study the IL-1 and IL-2 production; (2) in optimal conditions for IL production (incubation during 48 h in the presence of PHA and NHS) no effect of GH was observed on IL production; (3) in the absence of PHA GH acts at physiological doses (less than 100 ng/ml) by increasing the IL production. This effect of GH was optimized with a short time of incubation (16 h) and in the simplest conditions of cultures, that is to say in the absence of serum and of PHA: thus in the presence of GH 100 ng/ml the IL-1 production increases from 0.53 to 3.86 fmol (tubes) and IL-2 increases from 0.18 to 3.22 fmol (tubes). These differences are significant (p less than 0.001). We conclude that GH acts in vitro on mononuclear cells to induce IL production.