Interleukin-1α (IL-1α) and interleukin-2 (IL-2) levels were measured by radioimmunoassay in samples of conditioned medium from mononuclear cells taken from 20 normal subjects (14 adults ranging in age from 20 to 45 years and 6 children ranging in age from 3 to 11 years) and from 49 children with growth delay. Cultures were performed with 106 cells/ml in medium containing 1 % normal human serum and 4.8 g/l phytohemagglutinin M. The incubation was performed for 48 h in an atmosphere containing 5 % CO2. In normal subjects, the production of IL-lα was 38.5 ± 9.8 fmol/ml of conditioned medium (mean ± SEM) in 14 adults and 41.6 ± 3.0 fmol/ml in 6 children. The production of IL-2 was 46.9 ± 6.5 and 57.3 ± 10.5 fmol/ml, respectively. In the 16 patients with growth hormone (GH) deficiency studied before treatment, the production of ILs was significantly decreased in relation to the degree of deficiency. We observed a positive correlation between the produciton of IL-lα and the values of insulin-like growth factor I but not with serum GH values. IL-lα production was normalized after 15 days of substitutive GH therapy and IL-2 was normalized after 3 months of therapy. In 10 other patients with GH deficiency (4 with total and 6 with partial isolated GH deficiency) studied after long-term GH treatment (5 months or more), the mean of IL production was not significantly different from that of GH-deficient children treated for 3 months. In the 23 patients with constitutional delay of growth, we observed also a significant decrease in ILs compared to the control. No correlation was found between IL production and bone age ranging from 3 to 10 years. We conclude that GH is required for IL production.
The growth-promoting activity of serum was studied in 47 normal full-term newborns, comparing the effects of cord and of capillary serum upon the 3H-thymidine uptake into activated adult human lymphocytes. At birth the mean +/- SEM (TA) was significantly higher (P less than 0.001) in capillary serum (1.26 +/- 0.08 U/ml) than in cord blood (0.88 +/- 0.05 U/ml), the individual values being significantly correlated. The relatively low values in cord blood do not result from the presence of an inhibitor, nor from the cortisol levels. It may be concluded that study of cord blood is not the best means to measure growth-stimulating factors in newborns.
ABSTRACT Using [3H]thymidine incorporation into DNA of human lymphocytes in culture, we have shown that human serum contains an ultrafiltrable factor(s) that sensitizes the activation of lymphocytes by phyto haemagglutinin. This (these) factor(s) can replace either human serum or foetal calf serum in the culture. In addition, it permits the expression, and therefore the assay, of human somatomedin A peptides. In somatomedin assays we have shown that the assay using lymphocytes is a much more sensitive test than the assay using sulphation of chick embryo cartilage.
