ABSTRACT
Objective To explore the mechanism of lymphotactin(LTN) to exert mucosal adjuvant activity. Methods Complexes of chitosan-pVP1 and chitosan-pLTN were seperately prepared by co-cojugation method, then 50μg(DNA) of each complex was administered intranasally to male BALB/c mice 4times biweekly. Two weeks after the final immunization, mice were challenged with 3LD50 CVB3 to cause viral myocarditis, heart histopathological changes were examined 7 days later. Meanwhile, T cell immune responses, DC percentage and its membrane CD86 expression were monitored in spleen, mesenteric lymph node(MLN) and cervical lymph node(CLN). Results Co-immunizaiton with LTN remarkbly alleviated CVB3-induced cardial injury. This improvement was accompanied with enhanced T cell proliferation and IFN-γ-secreting ability, increased DC frequency and membrane CD86 expression both in spleen and mucosal draining lymph nodes( MLN, CLN). Conclusion LTN exerts its mucosal adjuvant function in augmenting specific T cell immune responses systemically and mucosally via DC enrichment in spleen, MLN and CLN and up-regulation of DC maturation.
ABSTRACT
AIM: To investigate lymphotactin (Lptn) gene transcription during acute cardiac allograft rejection and the inhibitory effect of cyclosporine A (CsA). METHODS: Graft specimens were harvested at indicated time to determine morphological changes by pathological examination. The grade of acute cardiac allograft rejection was evaluated by using modified Banff scoring system. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the Lptn mRNA expression in cardiac grafts. NFATc1 activity of splenocytes after transplantation was assessed by enzyme-linked immunoabsordent assay (ELISA). RESULTS: Prominent splenomegaly on day 3 posttransplantation was found in C57BL/6-Balb/c group. The extent of myocardial inflammatory infiltration was scored 2.667?0.577 at day 5 and 2.333?0.577 at day 7, respectively. Splenomegaly was ameliorated by CsA treatment, and the extent of myocardial infiltrate was scored 1.000?0.000 at day 5 and 1.333?0.577 at day 7, respectively. Lymphotactin mRNA was undetectable in cardiac isografts. Lymphotactin mRNA, which was inhibited partially by CsA, was upregulated strongly in acutely rejecting cardiac allografts at day 5 and day 7. Further studies demonstrated that NFATc1 activity in splenocytes, which markedly upregulated during acute rejection, was completely inhibited by CsA. CONCLUSION: Lptn appears to be a key chemokine of lymphocyte infiltration during acute allograft rejection. Inhibition of NFATc1 activity by CsA seems to decrease Lptn expression incompletely, suggesting that there was else mechanism to regulate Lptn expression other than NFAT pathway.
ABSTRACT
We previously showed that adenvirus-mediated lymphotactin (Ltn) gene transfer in vivo could improve the an-titumor efficacy of cytosine deaminase (CD) gene therapy significantly. In the precent study, we investigated the im-munological mechanisms involved in the enhanced antitumor efficacy. Upregulation of CD80 and CD54 on murine CT26 colon carcinoma cells was observed after combined transfection with adenovirus encoding CD (AdCD) and adenovirus encoding murine Ltn ( AdLtn) followed by administration of 5-PC in vitro. IL-2 and IFN-? level secreted by splenocytes increased significantly after the combination therapy. In vivo depletion analysis showed that both CD4~+ and CD8~+ T cells participated in the antitumor effect of the host with CD8~+ T cells being the main T cell subset responsible for the enhanced antitumor immune response. These data suggested that increased irnmunogenicity and efficient induction of antitumor immunity of the host might contribute to the enhanced antitumor effects of the combined Ltn and CD suicide therapy.
ABSTRACT
Adenovirus harboring E. coli. cytosine deaminase gene (AdCD) and adenovirus encoding with lymphotactin gene (AdLtn) were used for gene therapy in vivo. BALB/c mice were inoculated subcutaneously with CT26 colon adeno-carcinoma cells and 3 days later received combined injection of AdCD and/or AdLtn followed by continuous injection with 5-fluorocytosine(5-FC) 300mg/kg. The results demonstrated that mice received combined therapy developed tumors most slowly and survived longest when compared with mice treated with AdCD/5-FC, AdLtn, AdlacZ/5-FC or PBS. To further explain the immunological mechanism of the antitumor effects by the combined therapy, we found that combined treatment with suicide gene and Ltn gene therapy achieved maximal cytotoxic effects of nature killer cells and specific cy-totoxic T lymphocytes. FACS analysis of the tumor mass demonstrated that AdCD/5-FC in combination with AdLtn therapy increased the expression of H-2K~d and B7-1 expression on tumor cells. The CD4~+ and CD8~+ cells infiltrated in the tumor mass after combined therapy were significantly increased when measured by FACS analysis. Our results demonstrated that combined transfer of suicide gene and lymphotactin gene induce nonspecific and specific antitumor immunity of the host and elicit more potent antitumor effect.
ABSTRACT
AIM: To investigate the in vitro anti tumo r immune responses of dendritoma formed by mouse hepatocellular carcinoma cells and lymphotactin gene modified dendritic cells (DCs). METHODS: DCs prepared from mouse bone marrow were genetically mo dified by lymphotactin adenovirus, and fused with H22 cells by polyethylene glyc ol. RT-PCR and ELISA were employed to identify lymphotactin expression at mRNA a nd protein levels. The phenotypes and fusion efficiency were detected by FACS. T he stimulatory capacity of DC to T cells was detected by mixed leukocyte reactio n. The cytotoxicity activity against H22 cells was assayed by LDH method. RESULTS: Lymphotactin effectively expressed by DCLptn/H22 hybrid oma. DCLptn/H22 cells induced potent T cell proliferation effect and generated s trong CTL reaction against allogenic H22 cells. CONCLUSION: Lymphotactin genetic modification enhanced the in vitro immune activity of dendritoma.