Immune function in growth hormone-deficient children treated with biosynthetic growth hormone

Conflicting data regarding the immune function in growth hormone (GH) -deficient children or changes in immune parameters during substitutive GH therapy have been reported. We have studied the immune function in 13 patients with GH deficiency before and during treatment with biosynthetic GH (12 IU/m2 body surface/week) after 6 and 12 months of therapy. We found that the absolute number of total T lymphocytes and T-cell subsets (using monoclonal Ab as markers), Natural Killer cell activity (target K562) and response of lymphocytes to polyclonal mitogens (PHA, ConA, PWM) were all in the normal range and remained so after 6 and 12 months of therapy. The absolute number of B lymphocytes was in the normal range before treatment and after 6 months of therapy but dropped significantly after 12 months of treatment. Serum immunoglobulins (IgG, IgA, IgM) did not show a parallel drop and remained normal throughout the whole study. Our GH-deficient patients did not show any undue susceptibility to infections and our data thus seem to confirm that the immune function is basically intact in these children and that it is not suppressed by GH treatment. Although a drop in B lymphocytes was observed, the normal level of immunoglobulins and the normal functional response to PWM seem to demonstrate the maintenance of a normal humoral immune response.     

Craniofacial and acral growth responses in growth hormone-deficient children treated with growth hormone

OBJECTIVES: To investigate the effects of growth hormone (GH) therapy on craniofacial growth and body proportions in growth hormone deficient children. STUDY DESIGN: By using a cross-sectional study design, we investigated GH effects on craniofacial growth with photographic facial morphometrics, head circumference, and hand and foot size in 52 children with GH deficiency (GHD) treated with GH (0.27 mg/kg/wk) for 0.19 to 15.5 years, compared with untreated children with GHD and normal first-degree relatives. To detect disproportion and to correct for stature, age and height age (HA) SD scores were analyzed. RESULTS: Untreated subjects with GHD had retarded facial height and width (P values=.001) compared with normal controls; small head circumference for age and HA (P=.001); small hands for age (P<.001) that were large for HA (P=.003); and small feet for age (P<.001) that were normal for HA. When compared with normal controls, GH-treated subjects had proportional facial heights but narrower facial widths. Head circumference, however, increased disproportionately to height (P=.001), becoming large for stature, and increasing with duration of therapy and cumulative GH dose (P<.001). Hands and feet grew proportionately to height. CONCLUSION: Growth hormone treatment with conventional doses partially corrects craniofacial deficits and does not adversely affect hand and foot growth but appears to result in excessive head circumference growth.     

Suppression of immune function in growth hormone-deficient children during treatment with human growth hormone

Inasmuch as growth hormone is known to interact with the immune system, we studied immune functions including immunoglobulins, cell surface markers, mitogen responses, and polymorphonuclear cell function in eight children with growth hormone deficiency, ages 1 to 17 years, before and during treatment with human growth hormone for 12 to 16 months. Before treatment immune functions were normal in all children. Treatment with human growth hormone did not significantly affect serum immunoglobulins, polymorphonuclear cell function, or percent T cells. However, percent B cells decreased to subnormal levels in seven of seven patients. T helper/suppressor ratios decreased in all patients, to subnormal values in seven of eight patients; and mitogen responses decreased to below normal in all. The decline of percent B cells was transient in all patients, of T helper/suppressor ratios in seven of eight, and mitogen responses in five of eight patients. In vitro incubation of lymphocytes with growth hormone resulted in no changes in cell surface markers or mitogen responses. Although the depression of immune functions resulted in no increased rate of infections during the observation period, we do not know the possible effects of prolonged treatment and therefore caution against the indiscriminate use of human growth hormone. The effects of biosynthetically obtained growth hormone on immune function remain to be determined.     

Immune functions during treatment of growth hormone-deficient children with biosynthetic human growth hormone

Immune functions, including cell surface markers, interleukin-2 receptor levels and responses of lymphocytes to mitogenic stimulation were evaluated in seven growth hormone deficient children ages 4-15 years, during treatment with biosynthetically derived human growth hormone. Treatment resulted in a decrease in % B cells and in % T total cells and also decreases in most individual patients' mitogen responses and interleukin-2 receptor levels. Most of the changes noted were transient and similar to those previously demonstrated during pituitary-derived human growth hormone treatment. Although not resulting in overt clinical manifestations in our patients, we think that potential interactions between growth hormone and immune functions need to be considered by physicians treating children with growth hormone.     

Follow-up of antibodies to growth hormone in 210 growth hormone-deficient children treated with different commercial preparations

The aim of the study was to evaluate the immunogenicity of different commercial recombinant-growth hormone preparations. The presence of antibodies to growth hormone was tested in 210 growth hormone-deficient children at 6-month intervals during treatment for 6-66 months. The patients were treated with three preparations (groups A, B and C of 70 cases each) having the authentic growth hormone sequence. Groups A and B received hormone synthesized by the recombinant DNA technique in E. coli, while the group C preparation was produced in a mammalian cell line. The preparations showed poor immunogenicity and antibodies were found as follows: 1.4% in patients of group A (1 case: binding capacity 0.2mg/l and Ka 3.5 10⁷ 1 M^-1), 2.8% in patients of group B (2 cases; case 1 binding capacity 0.7mg/l and Ka 1.5 10⁷1M^-1; case 2 binding capacity 0.04mg/1 and Ka of 1.8 10⁸ and 6.5 10⁶ 1 M^-1), and 8.5% in group C (6 cases; binding capacity from 0.4 to less than 0.02 mg/ 1, Ka from 1.6 10⁷ to 3.8 10⁸ 1 M^-1). Only two patients of group C presented the antibodies in two subsequent examinations; in the other patients the positivity was found once. In all patients positive samples were found at intervals of 6-24 months after the start of therapy. In all antibody-positive patients growth velocity presented no decrease at the time of antibody detection and was never different to that of negative patients. We conclude that the three commercial preparations examined showed poor immunogenicity without clinical relevance.     

Humoral and cell-mediated immunity in growth hormone-deficient children: effect of therapy with human growth hormone

To delineate the role of growth hormone (GH) in the development and function of the immune system, immunological parameters including quantitative immunoglobulins, T and B lymphocytes, phytohemagglutinin lymphoproliferative response and delayed hypersensitivity skin tests were studied in nine GH-deficient children prior to GH therapy and at 2 months and 9 to 12 months following therapy. The phytohemagglutinin response (74.1 +/- 37.6, mean +/- SD), and the T rosette (58.3% +/- 9.4), B rosette (21.1% +/- 6.1), IgG (810 +/- 241 mg/dl), (IgA 140 +/- 85), and IgM (176 +/- 70) levels in GH-deficient children were comparable to age adjusted values in normal children. Following GH therapy the phytohemagglutinin response increased significantly at 9 to 12 months post-therapy, 123.2 +/- 51.9 versus 74.1 +/- 37.6, p less than 0.05. T and B rosettes, immunoglobulin concentrations, and hypersensitivity skin tests were not affected by GH therapy. Although an effect of GH was not demonstrable by these studies, a positive role of GH cannot be entirely excluded since total GH deficiency did not exist in all children.     

The effect of human growth hormone therapy on skinfold thickness in growth hormone-deficient children

Skinfold thickness (ST) was measured in 43 children with various forms of growth hormone (GH) deficiency during the first year of GH therapy. The average (and SEM) initial ST, expressed as standard deviation score (SDS) was 1.17 (0.25) for subscapular, 0.63 (0.18) for triceps, and 0.40 (0.21) for biceps ST. During therapy the average decrease is 1 SD. Children in the pubertal age group and those with partial GH deficiency showed smaller decreases. A larger decrease of triceps ST was associated with lower GH and insulin peaks, and lower age, bone age and initial weight-for-height. Some correlations between ST decrease and growth response in the first year were significant, but still too low to allow of reliable predictions. The same was true for other clinical parameters. These data indicate that a chronic lack of GH leads to unequal fat distribution, possibly due to different sensitivities to GH in the trunk and extremities. The variability of ST responses to GH therapy limits clinical applications.Abbreviations GH growth hormone - hGH human growth hormone - SDS standard deviation score - SDS_BA standard deviation score for bone age - SDS_CA standard deviation score for chronological age - SEM standard error of the mean - ST skin fold thickness - ST-SDS skinfold thickness, expressed as a standard deviation score - ST-log skinfold thickness, expressed as 100.log₁₀ (reading in 0.1 mm-18) - TSH thyroid stimulating hormone     

Cardiovascular effects of high-dose growth hormone treatment in growth hormone-deficient children

Growth hormone (GH) hypersecretion is associated with an increased incidence of cardiac hypertrophy and subclinical abnormalities of left ventricular (LV) function. The unlimited availability of biosynthetic GH has led to progressively increased dosage when treating GH-deficient children, raising the question of its cardiovascular effects during long-term therapy. We compared 22 children (8 girls, 14 boys), mean age 12.1 years (range 3–17 years) with GH deficiency who were receiving chronic GH treatment (GH group) with 22 normal controls matched for sex and body size in order to evaluate: (1) LV volume, mass, and systolic function by two-dimensional guided M-mode echocardiography; (2) LV diastolic function by pulsed-wave Doppler sampling of the transmitral flow; and (3) cardiac output and systemic vascular resistance by Doppler echocardiography. All patients had been on chronic GH therapy for 13.8±7.6 months (range 5–30 months) with an average dose of 0.95±0.12 IU/kg per week (range 0.69–1.17 IU/kg per week). Blood pressure did not differ between the two groups. LV volume, mass, ejection fraction, and mean velocity of circumferential shortening did not differ significantly between the GH group and controls; nor did the peak- and end-systolic meridional stress. All patients had a normal contractile state as estimated by the relation between mean velocity of circumferential shortening and end-systolic meridional stress. The LV filling parameters did not differ between the two groups, and there was no difference in cardiac index and systemic vascular resistance. These f9ndings suggest that long-term treatment with high doses of GH in GH-deficient children and adolescents does not lead to adverse cardiac effects. Whether longer-duration therapy could cause morphofunctional alterations of the left ventricle requires further investigation.     

Effect of growth hormone-releasing factor on growth hormone release in children with radiation-induced growth hormone deficiency

Five male children who received cranial irradiation for extrahypothalamic intracranial neoplasms or leukemia and subsequently developed severe growth hormone (GH) deficiency were challenged with synthetic growth hormone-releasing factor (GRF-44), in an attempt to distinguish hypothalamic from pituitary dysfunction as a cause of their GH deficiency, and to assess the readily releasable GH reserve in the pituitary. In response to a pulse of GRF-44 (5 micrograms/kg intravenously), mean peak GH levels rose to values higher than those evoked by the pharmacologic agents L-dopa or arginine (6.4 +/- 1.3 ng/mL v 1.5 +/- 0.4 ng/mL, P less than .05). The peak GH value occurred at a mean of 26.0 minutes after administration of GRF-44. These responses were similar to those obtained in children with severe GH deficiency due to other etiologies (peak GH 6.3 +/- 1.7 ng/mL, mean 28.0 minutes). In addition, there was a trend toward an inverse relationship between peak GH response to GRF-44 and the postirradiation interval. Prolactin and somatomedin-C levels did not change significantly after the administration of a single dose of GRF-44. The results of this study support the hypothesis that cranial irradiation in children can lead to hypothalamic GRF deficiency secondary to radiation injury of hypothalamic GRF-secreting neurons. This study also lends support to the potential therapeutic usefulness of GRF-44 or an analog for GH deficiency secondary to cranial irradiation.     

Diagnostic value of growth hormone-releasing hormone test in children and adolescents with idiopathic growth hormone deficiency

Average growth hormone (GH) peaks following an i.v. growth hormone releasing hormone (GHRH) 1–29 stimulation test were significantly lower in 48 children and adolescents with GH deficiency (GHD) than in 20 age-matched controls (15.2+12.7 vs 37.5+28.1 ng/ml, 2P<0.001). Twelve patients exhibited a low GH peak (<5 ng/ml), 27 demonstrated a normal response (>10 ng/ml) and 9 showed an intermediate rise in plasma GH (5–10 ng/ml). Six of the 12 patients with low GH response to the first GHRH stimulation failed to respond to two other tests immediately before and after a 1 week priming with s.c. GHRH. These subjects with subnormal GH increase at repeat testing had total GHD (TGHD) and multiple pituitary hormone deficiency (MPHD) and had suffered from perinatal distress. On the contrary, 26 of 27 patients with normal GH response to the first test had isolated GHD and only a minority (8/27) had signs of perinatal distress. It is concluded that perinatal injuries primarily damage pituitary structures and that a pituitary defect more probably underlies more severe forms (TGHD and MPHD) of GHD.Presented in part at the 7th Meeting of the Italian Society for Paediatric Endocrinology (Milan, 20–21 October 1989)     

Radioimmunoassay for type I procollagen in growth hormone-deficient children before and during treatment with growth hormone

Type I procollagen concentrations were measured by radioimmunoassay in sera from 14 growth hormone-deficient children before and during 12 months of treatment with human growth hormone. Basal procollagen levels were lower than those of control children and comparable to those of normal adults. With treatment, the mean procollagen level increased into the range of the control children and was significantly greater than the baseline level at 1, 2, 3, and 12 months (p less than 0.01; p less than 0.05). Although there was no significant statistical correlation between the growth velocity during treatment and the serum procollagen level, there was a suggestion that a high basal procollagen may be predictive of a less than optimal response to human growth hormone.     

The educational, vocational, and marital status of growth hormone-deficient adults treated with growth hormone during childhood

The goal of growth hormone therapy in childhood is to increase stature, thereby facilitating normal psychosocial development. To determine the social outcome of patients with growth hormone deficiency (GHD), we interviewed 116 adults with GHD across Canada, including 86 men and 30 women 18 to 38 years of age who were treated with growth hormone during childhood. The education of the 96 patients who had completed their formal education was similar to their siblings and to the general population. Of the patients in the labor force, 35.4% were unemployed; the unemployment rates for those patients less than 25 years of age and those 25 years of age or older were 45% and 23%, respectively, compared with national rates of 21.2% and 9.4% for the same age groups, respectively. Of the 90 patients with GHD who were not attending school, 70 lived with their parents or relatives. Only 15 patients were married; one was divorced. The percentage of patients with GHD who were married was less than 30% of the expected age-adjusted rate. No difference in the rate of employment or marriage was found between the patients with idiopathic isolated GHD and organic hypopituitarism. In summary, the achievements of patients with GHD seem to be normal in the education system, but the rate of employment and marriage are much lower than expected. This poor outcome was unrelated to the response to growth hormone therapy and emphasizes the need to develop strategies that lead to more satisfactory psychosocial integration of patients with GHD in adult life.     

Prediction of growth response in prepubertal children treated with growth hormone for idiopathic growth hormone deficiency

Several multiple regression models have been developed to predict the first-year growth response to human growth hormone (hGH) in children with growth hormone deficiency (GHD). It was the aim of this study to analyse the significance of various growth parameters for a height prediction model. Data from 148 prepubertal children with idiopathic GHD were evaluated. The prediction model was developed by means of univariate and stepwise linear regression analysis and an “all possible” regression approach using Mallow's C(p) statistics. Six out of eight selected variables had a significant influence on the first-year growth rate. The most important parameter was the difference between target height SDS and height SDS at the start of therapy (THSDS - HSDSC0), accounting for 23.95% and 25.74% of the variability. No other single variable or combination of variables was more informative than the variable THSDS - HSDSC0 alone. From these data, growth velocity for the first year of hGH treatment was estimated as 1.106 (THSDS - HSDSC0) + 6.8 cm/y ± 2.2 cm (SE), allowing a prediction for different intervals between THSDS and HSDSC0. This equation was validated in a small group of 18 GHD patients demonstrating a predicted vs. observed first-year growth rate of 9.4 ± 1.1 vs. 9.5 ± 2.6 cm/y. We conclude that the difference between THSDS and height SDS at the start of therapy is an important predictor of the first-year growth response in children treated with hGH for idiopathic GHD. Unlike in previous studies, additional parameters did not increase predictability.     

The dosage dependency of growth and maturity in growth hormone deficiency treated with human growth hormone

A group of 11 pre-pubertal growth hormone deficient patients were treated with human growth hormone over a period of 4 years. In 6 of the patients the dosage was 4 IU 3 times a week and in 5, 8 IU 3 times a week. Changes in height demonstrated that the "catch up" was significantly greater and of longer duration in the second group. In spite of a more rapid increase of bone age in the second group, the prognosis of final height had improved significantly at the end of the study period. A comparative study of the plasma concentrations significantly at the end of the study period. A comparative study of the plasma concentrations of T4, TSH, gonadotrophins and steroids, to see if the greater velocity of bone maturity in the second group could be due to contamination of the preparation by other could be due to contamination of the preparation by other hypophysary hormones, did not demonstrate significant differences between the groups.     

High prevalence of eosinophilia in growth hormone-deficient children

BACKGROUND: To determine the clinical significance of eosinophilia in growth-hormone (GH)-deficient children, a clinical study consisting of 72 children and adolescents (mean age 9 years and 6 months at diagnosis) with GH deficiency (GHD) was undertaken. Patients were treated with GH, along with supplementation for the combined deficiency in patients with multiple hormone deficiency. METHODS: A complete blood count and hemogram with microscopic examination of a peripheral blood smear was performed. RESULTS: Before treatment, differential eosinophil counts exceeded 5% in 30 subjects (41.7%) and absolute eosinophil counts were >350 /microL in 27 subjects (37.5%). Growth hormone therapy did not significantly affect eosinophil counts. There was an inverse relationship between absolute eosinophil count and peak GH value in response to the L-dopa stimulation test (n=65; Rs=-0.252; P=0.044). CONCLUSIONS: For the diagnosis of GHD, one should take into account that GH response to L-dopa stimulation can be selectively blunted in patients with eosinophilia.     

Plasma growth hormone response to growth hormone-releasing hexapeptide (GH-RP-6) in children with short stature

Eighteen children with short stature were evaluated for growth hormone (GH) reserve after pharmacological tests and a single iv injection of GH-RP-6. These children were divided into two groups: 10 were diagnosed as having idiopathic GH deficiency by classical stimulation tests (group A) and the remaining 8 (group B) were considered growth-retarded children with normal GH secretion, following conventional stimulation, but reduced endogenous GH secretion. The results were compared with a group of 12 normal children. As a group, patients in group A showed a lower GH response to GH-RP-6, while patients in group B had a similar response as normal controls. However, on an individual basis, a considerable degree of overlapping in responses among the three groups was evident. These data indicate that, on an individual basis, GH-RP-6 testing is not of diagnostic value in children suspected of having idiopathic GH deficiency.GH deficiency, GH-RP-6, short stature C Dieguez, PO Box 563, 15705 Santiago de Compostela, Spain