Macrophage activation of lymphoma-bearing mice by liposome-mediated intraperitoneal IL-2 and IL-6 gene therapy

Objective To investigate the antitumor mechanism of interleukin-2 (IL-2) an d interleukin-6 (IL-6) gene therapy. Methods Liposome encapsulated IL-2 DNA and IL-6 DNA were intraperitoneally (i.p.) injected into mouse lymphoma cell line (EL-4) lymphoma-bearing mice. Macrophage function (M phi) from the mice was assessed. Results Cytotoxicity, major histocompatibility (MHC) II expression and IL-l and TNF secretion of the macrophages all augmented after i.p. injection of liposome encapsulated IL-2 DNA or IL-6 DNA. More efficient activation of m acrophages was observed in mice treated with liposome encapsulated IL-2 DNA than IL-6 DNA. IL-2 gene therapy combined with IL-6 gene therapy showed th e maximal activation of macrophages in the lymphoma-bearing mice. Conclusion IL-2 and IL-6 gene therapy can relieve the supression of macroph ages of the lymphoma-bearing mice, and efficiently activate the antitumor i mmune responses.