Growth hormone treatment and immune function in short children with or without growth hormone deficiency

Abstract

Aim Immune functions in short children with or without GH deficiency and the effect of 1 year of GH treatment (0.5 u/Kg/week for GHD and 0.7 u/Kg/week in non-GHD patients) were studied.

Patients and methods Immune functions were studied in 9 non-GHD and 12 GHD children before and after 3, 6 and 12 months of GH therapy. Serum immunoglobulin levels were determined and peripheral blood mononuclear cells were isolated from heparinized blood for lymphocyte marker analysis (monoclonal antibodies and UV microscopy), lymphocyte stimulation and plaque-forming cell (PFC) assays. NK cell function was studied in 5 GHD and 3 non GHD patients before and after 3 and 6 months of GH.

Results The serum IgG, IgA and 1gM were normal in both groups of patients and did not change greatly with GH treatment. The percentages and absolute numbers of circulating lymphocytes, CD3+, CD4+, CD8+, Tac+ and CD16+ cells and the lymphocyte proliferation response to PHA, ConA and OKT3 were normal in both groups of patients and did not change significantly with GH treatment. There was a reduction to normal in the absolute number of lymphocytes and significant reductions in the percentages and absolute numbers of B-lymphocytes with GH treatment in the GHD but not the non-GHD children. The spontaneous IgG, IgA and IgM PFC response was similar in both groups of patients; IgG - and IgA - producing cells were increased at 3 months of treatment, while IgM production did not vary with treatment. However the PWM stimulated IgG and IgM PFC responses were significantly lower in GHD patients compared to non-GHD children and in the former, IgG but not IgA or IgM PFC improved after 12 months of GH treatment. The NK cell killing activity was diminished at low E:T in both group of patients compared to adult controls with no improvement with GH therapy.

Conclusions GHD is associated with increased circulating B-cells but reduced in vitro responsiveness to B-cell activating stimuli. Partial normalization occurs during GH replacement therapy.