Effects of GH replacement therapy on hematopoiesis and immune function: a placebo controlled study
Ilkay Cakir1, Fatih Tanriverdi1, Zuleyha Karaca1, Leylagul Kaynar2, Gulsah Elbuken1, Bulent Eser2, Kursad Unluhizarci1 & Fahrettin Kelestimur1
Objectives: It has been recently recognized that GH may have a role in hematopoiesis and immune system. However, there are conflicting data regarding the effects of GH deficiency (GHD) and/or GH replacement therapy in GH deficient patients on hematopoiesis and immune system. The aim of the present study was to investigate the peripheral blood cell counts, T- and B-lymphocyte subsets and immunoglobulin levels before and after GH replacement therapy in patients with adult onset GHD.
Methods: Twenty patients (7 males and 13 females) with GHD were enrolled into the study. All patients received appropriate hormonal replacement therapies for other deficient pituitary hormones except GH. Patients were treated with either recombinant human GH (rh GH) (13 patients) or placebo (7 patients) for 6 months. Hemoglobin, hematocrit, mean corpuscular volume, platelet, red blood cells, white blood cells, percent (%) neutrophil and lymphocyte were evaluated. Measurement of lymphocyte subsets CD3+, CD4+, CD8+, CD16+, CD19+ and CD45+ was performed by flow cytometry. Serum immunoglobulin concentrations (IgG, IgA, IgM) were also measured. All measurements were evaluated at baseline and after 6 months of therapy.
Results: All investigated indices were within normal reference ranges before treatment. Levels of IGF1 were significantly increased and reached to normal values after 6 months of therapy in rhGH treated group (P<0.05). Only red blood cell count were significantly increased after 6 months with rh GH replacement therapy (P<0.05), but not in placebo group. There were no significant changes in other evaluated parameters after rhGH replacement.
Conclusions: Present data shows that short term GH replacement therapy has no any clinically important effect on hematopoiesis and immune system. However, significant increase in red blood cell count after treatment suggests that long term GH replacement treatment may have a potential effect on hematopoietic parameters.