Antiproliferative activity of gamma-interferon combined with lipopolysaccharide on murine adenocarcinoma: dependence on an L-arginine metabolism with production of nitrite and citrulline.

Growth of the murine adenocarcinoma EMT6 was moderately inhibited by up to 32 units/ml of gamma-interferon (IFN-gamma). However, EMT6 growth was blocked by as low as 2 U/ml of IFN-gamma, when added with lipopolysaccharide. In the same time, the combination IFN-gamma + lipopolysaccharide induced synergistically the production of nitrite and citrulline by EMT6 cells. Synthesis of the two products was correlated with IFN-gamma concentrations. It required exogenous L-arginine and was inhibited by a methylated L-arginine derivative, NG-monomethyl-L-arginine. Inhibition was specific since urea synthesis was not reduced by NG-monomethyl-L-arginine. The L-arginine-dependent pathway was involved in EMT6 cytostasis mediated by IFN-gamma + lipopolysaccharide because cytostasis expression required L-arginine and was inhibited by NG-monomethyl-L-arginine.

Cytostatic product(s) released by activated macrophages, unrelated to interleukin 1, tumor necrosis factor alpha, and interferon-alpha/beta.

Murine peritoneal macrophages activated for cytotoxicity by trehalose dimycolate in vivo and lipopolysaccharide in vitro released cytostatic factor(s) against EMT6 target cells, in 8-hr conditioned medium (CM). The cytostatic factor(s) completely blocked DNA synthesis by EMT6 cells within 16 hr. Other cell lines are less sensitive (P815 and R-L929) or resistant (KB and HT29) to the cytostatic effect of CM. The anti-proliferative activity of CM had a MW greater than 10,000 Da, as judged by ultrafiltration. It was destroyed by proteases and strongly inhibited by P815 cell product(s). Conditioned media from nonactivated macrophages were not cytostatic against EMT6 cells. No relationship was found between cytostatic factor(s) in CM and interleukin 1 (IL-1), tumor necrosis factor alpha (TNF-alpha), and interferon-alpha/beta (IFN-alpha/beta): the growth of EMT6 cells was unaffected by Hu.r.IL-is and Hu.r.TNF-alpha and was only slightly inhibited by IFN-alpha/beta. Furthermore, cytostatic CM contained low levels of TNF and IFN activities. Finally, antibodies raised against murine IFN-alpha/beta had no effect on the cytostatic activity of CM.

Localization of a salmon calcitonin-like molecule in one type of ultimobranchial cells in the freshwater turtle Pseudemys scripta.

Immunohistochemical methods using affinity adsorbed antibodies raised against the three families of calcitonins (CT) were applied to ultimobranchial (UB) cells in situ to investigate the nature of the Chelonian calcitonin molecule and its distribution in the ultimobranchial bodies of the freshwater turtle, Pseudemys scripta. In this species, the UB glands were present on both sides and consisted of scattered cell clumps between epithelial vesicular structures. The neighboring parathyroid tissue also contained two components, the majority being composed of similar vesicles, with occasional solid cell cords evenly distributed. Calcitonin immunoreactivity was found in the cell clumps of the UB gland and in the cell cords of the associated parathyroid, but not in the epithelial component lining the vesicles or in the amorphous material which sometimes filled the lumen. Turtle calcitonin was exclusively of the salmon type, as determined by the negative results obtained in situ after the use of antibodies raised against human and porcine molecules. The salmon-like calcitonin content of the ultimobranchial area was estimated as 15.2 ng; however, the molecule was undetectable in the circulation. In this work we localize the quantitate a salmon-like CT molecule in one type of ultimobranchial and parathyroid cell of a reptile for the first time.