Production of Interleukin-6 by Anterior Pituitary Cellsin Vitro*

Abstract

We recently reported that the cytokine interleukin-6 (IL-6) is a potent stimulator of anterior pituitary hormone release in vitro. Since IL-6 is not normally detectable in the blood, we hypothesized that IL-6 may be produced by the anterior pituitary in situ and thereby affect hormone secretion through paracrine or autocrine mechanisms. The present study demonstrates that cultured anterior pituitary cells spontaneously secrete large quantities of IL-6 in vitro. IL-6 was detectable in the incubation medium within 2 h, and by 8 h of culture had attained concentrations of 2000-4000 U/ml.4 x 10(5) cells. IL-6 production was stimulated by phorbol myristate acetate (10-100 nM) approximately 2-fold and by lipopolysaccharide (0.001-10.0 micrograms/ml) 4-fold during 4-h incubations. In contrast, the cytokine recombinant human IL-1 alpha had no effect on IL-6 release by cultured pituitary cells. Freshly dissected hemipituitary tissue also secreted more than 3000 U/ml IL-6 during a 4-h incubation. This secretion was enhanced 3-fold by 10 micrograms/ml lipopolysaccharide. Our results suggest that the anterior pituitary may produce IL-6 in situ, where it may function as an intrapituitary releasing factor.

History and perspectives of pituitary folliculo-stellate cell research

“…Moreover, it also largely reduces the IL-6 production in S-100 þ MHC-class II þ and S-100 þ MHC-class II populations (80). Thus, paracrine communication between FS cell subpopulations (80) might be an important condition for achieving the high IL-6 production rates as observed in pituitary cells in vitro (13,81).…”

Interleukin‐6 an endocrine cytokine

“…IL-6 also potentiates GRF-stimulated GH release and TRH-stimulated prolactin secretion (Spangelo et al, 1989). IL-6 is secreted by primary cultures of normal rat anterior pituitary cells with the major source of synthesis and release from the folliculo-stellate cells (Vankelecom et al, 1989;Spangelo et al, 1990a). Folliculo-stellate cells do not secrete hormones and have characteristics in common with monocytic phagocytes.…”

Involvement of the gp130 cytokine transducer in MtT/S pituitary somatotroph tumour development in an autocrine-paracrine model

“…This occurs also in the pituitary gland, where many studies have demonstrated not only the expression of gp130 mRNA (6) but also the expression of specific receptors and synthesis of gp130 cytokines in different types of pituitary cells (reviewed in [7][8][9][10], providing the cellular and molecular basis for an auto-paracrine mechanism of regulation of pituitary function. Particularly, several groups have demonstrated IL-6 production and the presence of IL-6 mRNA in anterior pituitary cells (11,12). IL-6 production has been shown to be localized to folliculostellate (FS) cells in normal pituitary tissue (12), and to the tumour cells themselves in the case of pituitary adenomas (reviewed in 9, 13).…”