ESPE Abstracts

Background: As well as acting on longitudinal growth, growth hormone (GH) also has a number of metabolic effects, and is involved in the regulation, functioning and development of the immune system.

Aims: To evaluate the immune profile in GH-deficient children after 6 months’ GH treatment.

Method: A total of 44 children were examined before and after a six-month course of treatment with rhGH (0.03 mg/Kg per day). Levels of IGF1 and IGFBP3 were measured, and both the humoral immune profile (IgM, IgG, IgA, C1-inhibitor y serum complements C3 and C4) and the cell immune profile (WBC, differential leukocyte formula: lymphocytes, monocytes, total neutrophils, and CD3+, CD19+ and NK lymphocyte subpopulations) were investigated. A study was also made of CD4+ and CD8+ lymphocyte subpopulations grouped by positive cell counts above and below normal values. Data were subjected to Student’s t test and to Wilcoxon’s T-test for parameters exhibiting non-normal data distribution (total lymphocytes and NK cells), with a significance level of P<0.05.

Results: After 6 months’ GH therapy, a significant reduction was observed in IgG and IgM, together with a significant increase in IGF1 (P<0.05). A moderate decline in CD3+, CD4+, CD8+, CD19+ and NK cell levels was also recorded. Analysis of CD4+ and CD8+ lymphocyte subpopulations grouped by positive cell counts above normal values revealed significantly elevated levels prior to treatment; after 6 months’ treatment, values had fallen to levels not significantly different from normal. Subpopulations grouped by positive cell counts below normal values also rose to near-normal values after treatment.

Conclusions: These findings confirm changes in the immune system of GH-deficient children treated with rhGH. GH exerts immunomodulatory effects, and plays an important role in homeostasis, affecting the immune system; GH therapy normalises peripheral-blood CD4+ and CD8+ levels. The precise mechanism through which GH modulates the immune system remains unknown, and should be addressed in future, broader-based research.