2. Department of Immunology and Microbiology, National Defense Medical College, Namiki 3-2, Tokorozawa, Saitama 359- 8513, Japan.
Background: The administration of recombinant human growth hormone (rhGH) has been reported to restore the immune function due to GH deficiency (GHD). We herein investigated the phenotypic characterization, interferon (IFN)-γ production ability, and apoptosis of peripheral blood mononuclear cells (PBMCs) from patients with idiopathic GHD treated with rhGH to elucidate the effect of rhGH therapy on Th1 immune responses.
Methods: PBMCs were obtained from either 14 GHD patients treated with rhGH, 22 healthy children or five healthy adult volunteers. The lymphocyte subsets were analyzed by a flow cytometric analyzer and cultured with anti-CD3 antibody, interleukin (IL)-2 and IL-12, or staphylococcal enterotoxin B, and thereafter the IFN-γ levels were evaluated.
Results: The proportions of CD57+ T cells and CD56+ NK cells increased more in the patients than in healthy children. The IFN-γ production in the lymphocytes from the patients was also greater than that from healthy children. The CD3- stimulated lymphocytes from the patients were less susceptible to apoptosis. When the lymphocytes from healthy adults were cultured with anti-CD3 antibody and various concentrations of rhGH, the IFN-γ levels in the culture supernatants increased in a dose-dependent manner.
Conclusions: These findings suggest that rhGH therapy can enhance the IFN-γ production of lymphocytes probably due to a proportional increase in the number of CD57+ T cells and CD56+ NK cells as well as due to the inhibition of lymphocyte apoptosis.
Keywords: growth hormone, CD57+ T cell, CD56+ NK cell, IFN-γ , apoptosis