Recombinant human

growth hormone stimulates B cell immunoglobulin synthesis and proliferation in serum-free medium Akira Yoshida, Chihiro Ishioka, Hajime Kimata and Haruki Mikawa Department of Pediatrics. Faculty of Medicine. Kyoto University, Kyoto, Japan

Yoshida A, Ishioka C, Kimata H, Mikawa H. Recombinant human growth hormone stimulates B cell immunoglobulin synthesis and proliferation in serum-free medium. Acta Endocrinol 1992:126:524-9. ISSN 0001-5598 In order to investigate the effects of growth hormone on human B cells, we studied immunoglobulin synthesis and [ 3H]-thymidine uptake by B cell lines, IM-9, GM-1056 and CBL, and purified tonsil B cells.

Cells were cultured in a serum- and albumin-free medium, Cosmedium-001 to exclude interaction between a certain growth-promoting substance and any unknown substances that serum may contain. GH enhanced IgG synthesis and [3H]-thymidine uptake by IM-9 cells, IgA synthesis by GM-1056 cells and IgM synthesis by CBL cells in a dose-dependent fashion. This was not a non-specific effect of protein in GH, since equivalent or higher concentrations of proteins such as bovine serum albumin, interleuki\x=req-\ 2, interleukin-5, granulocyte/macrophage colony-stimulating factor, or erythropoietin did not stimulate B cell lines. Moreover, the rabbit anti-GH antibody blocked the enhancing effect of GH, while normal rabbit antibody failed to do so. GH also enhanced immunoglobulin synthesis (IgG and IgM) and thymidine uptake by Staphylococcus aureus Cowan strain I-activated tonsil B cells. These results indicate that GH has a direct stimulating effect on B cells, and, in addition to its endocrinological function, GH may also act as an immunoregulatory cytokine. Akira Yoshida, Department of Pediatrics, Kyoto University Hospital, Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606, Japan

A number of authors have shown that normal human thymic and peripheral lymphocytes, as well as the human lymphoid cell line IM-9, have binding sites for GH ( 1 -4). Human lymphocytes appear to have only high affinity receptors with around 7000 binding sites per cell and an affinity constant of 1.5 x 109 l/mol (3). IM-9 has 4000 binding sites per cell with an affinity constant of 1.3 xlO9 l/mol (1). The interaction of GH with the immune system has been reported by numerous investigators (5-19). Injec¬ tion of anti-GH serum into mice resulted in thymic atrophy and wasting disease (7). It has also been reported that GH-deficient mice had smaller thymic glands (8). Recently several reports have shown the new pictures of GH effects on immunoregulation. GH aug¬ mented the production of 02 by porcine macrophages in vitro and by hypophysectomized rat macrophages in vivo (9). In aged dogs, injections of GH retarded thymic aging and and augmented synthesis of thymulin (10). In humans, there have been conflicting reports of an association between GH and immune modulation. While a number of immune events are normal in GH-deficient patients (11, 12), several immunological alterations in these patients have been described, including hypogammaglobulinaemia (13) or reduced NK activity (14). ~

However, only limited reports have appeared on the effects of GH on lymphocytes in vitro. GH-induced

proliferation of peripheral blood lymphocyte ( 15, 16), Tcell leukemic lymphoblasts (17) and PHA-stimulated normal and leukemic T lymphocyte (18).

In contrast, there have been few reports on the effects of GH on B lymphocytes. Mérimée et al. (19) reported that GH stimulates B lymphocyte proliferation of normal subjects activated by EB-virus. In those studies, the in vitro incubation media utilized some type of serum such as fetal calf serum. Fetal calf serum contains many factors and hormones which may interact with a given growth factor or affect B cell responses (20, 21). The purpose of our study was to clarify whether GH had any direct effect on B cells. Therefore we used a serum-free medium (Cosmedium) and studied the effect of GH on thymidine uptake and Ig synthesis of B cells and B lymphoblastoid cell lines. We will now show that GH stimulates B cell growth and immunoglobulin production.

Materials and methods

Reagents and medium The following human recombinant cytokines and anti¬ body were kindly provided by each company or institute without any bovine serum or fetal calf serum: methionine-free growth hormone (GH) and rabbit anti-GH

QH stimulates B

acta endocrinologica 1992. 126

antibody (Sumitomo Pharmaceuticals, Osaka, Japan), interleukin (IL)-2 (Takeda Chemical Industries, Osaka, Japan), IL-5 (Suntory Research Center, Osaka, Japan), granulocyte-macrophage colony-stimulating factor (GM-CSF, Sumitomo Pharmaceuticals) and erythropoietin (Epo, Kirin Brewery Co. Ltd., Gunma, Japan). Bovine serum and normal rabbit serum were purchased from Nakalai Chemicals (Kyoto, Japan). Staphylococcus aureus Cowan strain I (SAC) was purchased from Calbiochem (La Jolla, CA). The culture medium was Cosmedium-001 (Cosmedium, Cosmobio Co., Ltd., Tokyo, Japan). Cosmedium contains 0.1 mg/1 hypoxanthine, 0.025 mg/1 thymidine, < 5 mg/I human transferrin, < 5 mg/1 bovine insulin,

Recombinant human growth hormone stimulates B cell immunoglobulin synthesis and proliferation in serum-free medium.

In order to investigate the effects of growth hormone on human B cells, we studied immunoglobulin synthesis and [3H]-thymidine uptake by B cell lines,...
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