Immunologic studies in children with idiopathic short stature before and during growth hormone therapy. Dutch Growth Hormone Working Group

In 34 children with idiopathic short stature (ISS) we studied parameters of humoral and cellular immunity before and during growth hormone (GH) therapy. The patients were treated with recombinant human GH 3.0 or 4.5 IU/m2 body surface/day, 6 times/week. Leucocyte and lymphocyte counts, percentages of neutrophils, eosinophils, basophils and monocytes were available up to 4 years of therapy (n = 34) and lymphocyte subsets and serum immunoglobulins during the first year of treatment (n = 16). Differences between the measurements at the start and during therapy were tested by a mixed model ANOVA to repeated measurements. Before the start of GH therapy all parameters of immunity were within the normal range in these children. During the first months of treatment the leucocyte and lymphocyte counts decreased and at 6 months were significantly lower than at the start (p = 0.003 and p = 0.006, respectively). Thereafter leucocyte numbers no longer differed from baseline. Lymphocytes were again lower at 36 months (p = 0.001). The percentages of neutrophils, eosinophils, basophils, monocytes and lymphocyte subsets did not change during therapy. Serum IgA concentrations showed a transient decrease at 3 and 6 months of GH therapy (p = 0.01 and p = 0.02). The observed changes were not related to GH dosage or height velocity. We conclude that GH treatment in children with ISS induced a small decrease in leucocyte and lymphocyte counts and serum IgA concentrations.