Objective To prepare a new type of chitosans nanoparticles(PEG/CS-EPI NPs),which contains epirubicin and modified by PEG.Furthermore,to investigate the anticancer activity of the NPs in vitro and in vivo.Methods The ionic gelation technique was employed to prepare the PEG/CS-EPI NPs and CS-EPI NPs.The particle size and shape were illustrated respectively by laser scattering and transmission electron microscopy.The proliferation of nasopharyngeal carcinoma cells was detected by MTT assay;The mouse model of implantation murine sarcoma cells(S-180) was applied to evaluate the anticancer effectiveness of PEG/CS-EPI NPs and CS-EPI NPs in vivo.Results The PEG modified CS NPs were discrete and uniform spheres with average diameter of 322.1 nm.The rate of drug loading and encapsulation is 13% and 74% respectively.The results of the anticancer tests showed a sustained cytotoxicity of loading drug NPs on nasopharyngeal carcinoma cells in vitro and the stealth nanoparticles was more powerful than ordinary nanoparticles on the inhibitory potency in vivo.Conclusion Stealth chitosan nanoparticles as compared with ordinary chitosan nanoparticles seems to be a potential candidate of chemotherapy drug carriers.

Objective: To investigate the role and mechanism of histamine in regulation of C57BL/6 mice spleen derived LAK activity in vivo. Methods: The C57BL/6 mice carrying B16 pulmonary metastatic melanoma were treated with LAK/IL 2/histamine therapy or LAK/IL 2 therapy with the aim of evaluating both anti tumor responses in vivo. Results: It was found that the addition of histamine effectively potentiated the anti metastatic effect produced by LAK/IL 2 therapy and induced regression of NK resistant B16 pulmonary metastatic melanoma. Survival period was significantly prolonged in mice receiving LAK/IL 2/histamine as compared with LAK/IL 2 therapy alone. The effect of histamine was completely blocked by H 2 R antagonist ranitidine, and mimicked by dimaprit, a H 2 R agonist. Conclusion:Histamine, via specific activation of H 2 R, may be an important regulator of LAK cells activity; histamine and LAK/IL 2 synergistically induce more potent antitumor efficacy in vivo .