Effect of Growth Hormone on the Metabolism of Thymus and on the Immune Response Against Sheep Erythrocytes

Abstract

The effect of pituitary growth hormone on the biosynthesis of DNA in the thymus and other lymphoid organs, as well as the ability of the rat to respond immunologically to sheep red blood cells, has been evaluated. There is a marked reduction in plaque-forming cells, hemagglutination titers, and DNA synthesis in animals when examined at 15 wk after hypophysectomy. Administration of bovine growth hormone (BGH) leads to the enhancement of DNA synthesis in lymphoid organs and recovery of the immune response. Similar effects of the hormone are observed in plateaued rats. Injection of rabbit anti-BGH globulins, in contrast to normal rabbit globulins, over 5 days causes a drop in the weight of the thymus and in the rate of DNA synthesis in this organ. The thymus is also the organ in which stimulation of DNA synthesis is observed at a time period earlier than the spleen and lymph nodes after a single injection of BGH. The hormone stimulates not only the incorporation of thymidine-3H into DNA in the cortical cells, but also the incorporation of sodium sulfate-35S into TCA-insoluble biopolymers reported to be elaborated in the medullary area of the thymus. An in vitro system for the action of BGH on the thymus has been described. There is an obligatory requirement for calcium, but not for fetal calf serum in the medium for the hormone effect. An early action of the hormone is the enhanced incorporation of uridine-G-3H into RNA in thymocytes which is followed by a stimulation of the synthesis of proteins and DNA. The stimulatory action of growth hormone on RNA synthesis is not because of a facilitated uptake of the radioactive uridine by the cells under hormonal influence, a mechanism by which insulin is observed to increase RNA synthesis in thymocytes in vitro. The action of growth hormone on thymocytes is specific, since thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and heat-inactivated growth hormone are not effective. BGH has also a beneficial action on the regeneration of the thymus and spleen in starved rats.

Effect of Elevated Growth Hormone Concentrations on the Phenotype and Functions of Human Lymphocytes and Natural Killer Cells

“…It has been postulated that growth hormone (GH), a 22-kD protein synthesized by the adenohypophysis, has immunostimulatory properties [1,2]. Studies in hypophy- increased activities of cytotoxic T lymphocytes and NK cells have been observed in vitro when lymphoid cells are incubated with GH [8] and in vivo after GH substitution in GH-deficient patients and mice [9,10].…”

Antiorthostatic Suspension Stimulates Profiles of Macrophage Activation in Mice

“…For instance, growth hormone possesses immunopotentiating activities and is produced as a component of the many host stress responses [27]. Since growth hormone and IFN-Á share many leukocyte-activating properties, including stimulating thymocyte proliferation [28], IL-2 production [29], the oxidative burst by macrophages [30] and neutrophils [31], and natural killer (NK) cell activity [32], it is possible that immunopotentiating hormones could contribute to the enhanced resistance we observed.…”

Production of Interleukin-1α and Interleukin-2 by Mononuclear Cells from Children with Growth Delay in Relation to the Degree of Growth Hormone Deficiency: Effects of Substitutive Treatment

“…A number of observations have indicated that growth hormone (GH) has an important influence on the im mune process [1][2][3][4]. More recent studies have described a role of GH in the maintenance of humoral and cellmediated immune reactions [5,6].…”