YAC 1 cells

To clarify the mechanisms of antitumor actions of various chitosans, we examined the cytotoxic activity against YAC-1 (NK cell-sensitive target ceils) or sarcoma 180 cells by intestinal intraepithelial lymphocytes (lELs) or splenic lymphocytes treated various chitosans. Treatment of lELs with oligochitosan (10 to 1000 jlg/mL), chitosan-21 (10 to 1000 jXg/mL), or chitosan-46 (10 to 1000 jXg/mL) enhanced their c>i otoxic activity against YAC-1 cells compared with that of untreated lELs Fig. (12) . 

IELs isolated from mice orally administered oligochitosan, chitosan-21, or chitosan-46 at 100 mg/kg enhanced the cytotoxic activity against YAC-1 cells, but the IELs isolated from chitosan-130-treated mice had no effect Table (8) . 

Yu Liping et al studies ss s inhibition of cancer. Test in vivo showed that ss could indirectly inhibit S180 cancer cells in mice with S180 cancer.Test in vitro showed that ss could directly kill cancer cells. Its mechanism may be that ss can inhibit the DNA synthesis in SI80 and YAC-1 cells and have obvious cytotoxic reaction to K562 and YAC-1 cells. 

NKactivity 1.5x10 /100 pi of spleen T cells and 1.5x10 /50 plof Cr-labeled YAC-1 cells were cultured in the presence or absence of AGE in a NUNC round-bottom micro-plate. After 4 and 24 h incubation, the mixture was centrifuged and the released Cr in the supernatant was counted in a gamma-counter and the cytotoxicity was determined. 

Moniewska A, Szyba K, Jazwiec B, et al. 1989. Chrysotile A affects YAC-1 cytolytic activity of spleen cells. Arch Imm Et Therap 37 61-68. 

Greenlee, A.R., R.A. Brown and S.S. Ristow. Nonspecific cytotoxic cells of rainbow trout (Oncorhynchus mykiss) kill YAC-1 targets by both necrotic and apoptotic mechanisms. Dev. Comp. Immunol. 15 153 -164, 1991. 

An important immune function to evaluate in the context of immuno-deficiency, and one that represents a form of nonspecific immunity/host resistance, is the function of natural killer (NK) cells. NK cells are lymphocytes distinct from either B-cells or T-cells, which contribute to immunocompetence by mediating major histocompatibility complex-independent cytotoxicity (Lotzova 1993). For the purposes of these studies, a combined measurement of both basal and augmented NK cell function was used. In this assay, murine splenoc5des were exposed for 24 hours to various concentrations of drugs in the presence or absence of an optimum concentration of recombinant IL-2 (Thomas et al. 1993). The cells were then washed and cocultured for 4 hours with radiolabeled YAC-1 tumor cells (a murine NK-sensitive cell line). Tumor cell lysis was quantitated as described above for the CTL procedure. 

After activation by expressed sap of . purpurea macrophages showed cytotoxic effects to tumour cells in vitro. Cell-mediated cytotoxicity was observed in cocultures of tumour cells (ABLS-8.1, Yac-1, L12-10) with bone marrow macrophages and . purpurea expressed sap [144]. An antitumour effect of the expressed sap has also been found in vivo after oral application to mice with Meth A tumour [143]. 

AGE (0.25-1.0 v/v %) treatment enhanced approximately two-fold the NK cell activity of the T cell fraction of mouse spleen cells against mouse lymphoma (YAC-1) [24]. A protein fraction of AGE (2.5-10 Xg/ml) also enhanced approximately two-fold the NK cell activity against YAC-1 (unpublished data). Morioka et al. reported that a protein fraction of AGE enhanced the cytotoxicity of human peripheral blood lymphocytes against both NK-sensitive K562 and NK-resistant M14 cell lines [23]. A more remarkable enhancement was observed when a protein fraction was administered together with a suboptimal dose of IL-2 (10 U/ml) combination treatment of a protein fraction (5 Xg/ml) plus IL-2 for 72 h generated lymphokine-activated killer activity equivalent to that produced by 100 U/ml IL-2 alone against M14. 

Marschall P, Malik N, Larin Z (1999) Transfer of YACs up to 2.3 Mb intact into human cells with polyethylenimine. Gene Ther 6 1634-1637... 

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