ABSTRACT
The role of mouse liver NK1.1 Ag(+) T (NKT) cells in the antitumor effect of alpha-galactosylceramide (alpha-GalCer) has been unclear. We now show that, whereas alpha-GalCer increased the serum IFN-gamma concentration and alanine aminotransferase activity in NK cell-depleted C57BL/6 (B6) mice and B6-beige/beige mice similarly to its effects in control B6 mice, its enhancement of the antitumor cytotoxicity of liver mononuclear cells (MNCs) was abrogated. Depletion of both NK and NKT cells in B6 mice reduced all these effects of alpha-GALCER: Injection of Abs to IFN-gamma also inhibited the alpha-GalCer-induced increase in antitumor cytotoxicity of MNCS: alpha-GalCer induced the expression of Fas ligand on NKT cells in the liver of B6 mice. Whereas alpha-GalCer did not increase serum alanine aminotransferase activity in B6-lpr/lpr mice and B6-gld/gld mice, it increased the antitumor cytotoxicity of liver MNCS: The alpha-GalCer-induced increase in survival rate apparent in B6 mice injected intrasplenically with B16 tumor cells was abrogated in beige/beige mice, NK cell-depleted B6 mice, and B6 mice treated with Abs to IFN-gamma. Depletion of CD8(+) T cells did not affect the alpha-GalCer-induced antitumor cytotoxicity of liver MNCs but reduced the effect of alpha-GalCer on the survival of B6 mice. Thus, IFN-gamma produced by alpha-GalCer-activated NKT cells increases both the innate antitumor cytotoxicity of NK cells and the adaptive antitumor response of CD8(+) T cells, with consequent inhibition of tumor metastasis to the liver. Moreover, NKT cells mediate alpha-GalCer-induced hepatocyte injury through Fas-Fas ligand signaling.
Subject(s)
Antineoplastic Agents/administration & dosage , Galactosylceramides/administration & dosage , Hepatocytes/immunology , Hepatocytes/pathology , Liver Neoplasms, Experimental/prevention & control , Liver Neoplasms, Experimental/secondary , Alanine Transaminase/blood , Animals , Antibodies, Monoclonal/administration & dosage , Antigens/immunology , Antigens, Ly , Antigens, Surface , Antineoplastic Agents/antagonists & inhibitors , Antineoplastic Agents/toxicity , Cytotoxicity, Immunologic/genetics , Enzyme Activation/immunology , Fas Ligand Protein , G(M1) Ganglioside/immunology , Galactosylceramides/antagonists & inhibitors , Galactosylceramides/toxicity , Growth Inhibitors/administration & dosage , Growth Inhibitors/toxicity , Growth Substances/administration & dosage , Growth Substances/toxicity , Immune Sera/administration & dosage , Injections, Intralymphatic , Injections, Intravenous , Interferon-gamma/antagonists & inhibitors , Interferon-gamma/blood , Interferon-gamma/immunology , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Killer Cells, Natural/pathology , Lectins, C-Type , Leukocytes, Mononuclear/immunology , Ligands , Liver Neoplasms, Experimental/genetics , Liver Neoplasms, Experimental/pathology , Lymphocyte Count , Lymphocyte Depletion , Male , Melanoma, Experimental/immunology , Melanoma, Experimental/mortality , Membrane Glycoproteins/biosynthesis , Mice , Mice, Inbred C57BL , Mice, Inbred MRL lpr , Mice, Mutant Strains , NK Cell Lectin-Like Receptor Subfamily B , Proteins/immunology , Spleen , Survival Analysis , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolism , T-Lymphocyte Subsets/pathology , Tumor Cells, Cultured/transplantationABSTRACT
We examined whether pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) affected 5-fluorouracil-induced thrombocytopenia without inducing more severe intimal thickening after injury to rat carotid arteries. Rat carotid arteries were injured using a balloon catheter on day 0. 5-Fluorouracil (100 mg kg(-1)) or vehicle was intravenously administered on day 1 in balloon-injured rats. PEG-rHuMGDF (100 microg kg(-1)) or vehicle was intravenously administered once a day on days 1-5 to balloon-injured rats given 5-fluorouracil or vehicle. 5-Fluorouracil (100 mg kg(-1), i.v.) caused a significant decrease in the platelet count from day 3 and peaked on days 7-9 in balloon-injured rats. PEG-rHuMGDF (100 microg kg(-1), i.v.) reduced this decrease on days 9 and 11. The administration of PEG-rHuMGDF did not accelerate the intimal thickening of balloon-injured arteries in rats treated with 5-fluorouracil compared with control balloon-injured rats. PEG-rHuMGDF did not increase plasma tumour growth factor-beta1 (TGF-beta1) from days 0-9 in balloon-injured rats compared with control balloon-injured rats. These results suggest that PEG-rHuMGDF ameliorated 5-fluorouracil-induced thrombocytopenia without accelerating the intimal thickening of balloon-injured arteries.
Subject(s)
Carotid Arteries/drug effects , Fluorouracil/administration & dosage , Polyethylene Glycols/pharmacology , Thrombocytopenia/prevention & control , Thrombopoietin/pharmacology , Animals , Blood Platelets/drug effects , Carotid Arteries/pathology , Catheterization , Fluorouracil/adverse effects , Humans , Male , Rats , Rats, Sprague-Dawley , Recombinant Proteins/pharmacology , Thrombocytopenia/chemically induced , Time Factors , Transforming Growth Factor beta/blood , Transforming Growth Factor beta/drug effects , Tunica Intima/drug effects , Tunica Intima/pathologyABSTRACT
Previous studies have shown that pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) at suprapharmacological dose induces a mild transient decrease of red blood cell counts according to thrombopoiesis in normal mice. To unravel the mechanism underlying this mild transient decrease of red blood cells, we have studied the effect of PEG-rHuMGDF on the circulating plasma and blood volume, and the serum biochemical parameters of anaemia and splenectomy. Also, we have performed histological studies of the bone marrow and the spleen of PEG-rHuMGDF-treated rats. PEG-rHuMGDF (300 microg kg(-1)]) or vehicle was subcutaneously administered to rats once a day for up to five days. From day 6 after the start of PEG-rHuMGDF administration, the platelet counts and plateletcrit levels were significantly increased, reaching peak values on day 10, and recovering to normal by day 20. The red blood cell counts and the haematocrit levels were significantly decreased on day 6 to 13. The decreases in red blood cell levels and haematocrit produced by PEG-rHuMGDF treatment were mild and had recovered by day 15. The plasma and blood volumes were significantly increased on day 10 in PEG-rHuMGDF-treated rats. No alteration of the serum biochemical parameters for anaemia, iron or total bilirubin, were observed on day 10. The histological examination on day 10 revealed a marked increase in megakaryocytes and a slight decrease in erythropoiesis in the bone marrow of rats that received PEG-rHuMGDF (300 microg kg(-1)). There was also a slight increase in splenic megakaryocytes and erythropoiesis. The decrease of red blood cells by PEG-rHuMGDF was not affected by splenectomy. These results suggest that the mild transient decrease of red blood cells induced by PEG-rHuMGDF treatment for up to five days is based mainly on the increases in the plasma and blood volume. These events are secondary changes due to the regulation of the excess production of megakaryocytes in the marrow and the peripheral platelets.
