ABSTRACT
Objective To explore the mechanism by which the anti-human P185erbB2 scFv-Fc-IL-2(HFI)modulates tumor surface molecules and activates immune effector cells in vitro. MethodsMTT assay was used to test the proliferation and the LAK-like cytotoxicity. Flow cytometry assay was used to test the expression of ICAM-1, Fas and erbB2 receptors in tumor cells and the expression levels of CD molecules FasL and LFA-1 in human PBMC. Antibody-dependent cell-mediated cytotoxicity(ADCC)mediated by HFI against SKOV3, MCF-7 and SGC-7901 tumor cells was explored hv LDH release assay. Results The expression levels of ICAM-1 and Fas on SKOV3 cell treated with HFI were upregulated, from 24.85％ and 0.53％ to 85.36％ and 59.19％ respectively, while the expression levels of erbB2 on SKOV3, MCF-7 and SGC-7901 tumor cells treated with HFI were downregulated, from 98.48％, 42.60％ and 36.66％ to 94.01％,30.95％ and 12.36％ respectively. HFI could significantly enhance the proliferation activity of human PBMC, and CD3+ CD8+ T cells and CD3- CD16+ CD56+ NK cells were elevated, from 24.37％ and 6.90％ to 38.80％ and 13.45％ respectively. The expression levels of CD25, LFA-1 and FasL were significantly enhanced from 3.99％, 86.52％ and 5.02％ to 12.96％, 99.06％ and 16.19％. The LAK-like cytotoxicity of human PBMC treated with HFI against SKOV3, MCF-7,SGC-7901 tumor cells was significantly improved:HFI was effective in mediating ADCC against SKOV3,MCF-7 and SGC-7901 tumor cells which expressed high,medium and low levels of erbB2,respectively,and HFI-induced ADCC was correlated with the degrees of erbB2 expression on the tumor cells. Conclusion The expression levels of ICAM-1 and Fas on SKOV3 cell treated with HFI are significantly upregulated. The expression levels of erbB2 on SKOV3, MCF-7 and SGC-7901 tumor cells treated with HFI are downregulated. HFI can significantly enhance the proliferation activity of human PBMC. The LAK-like eytotoxicity of human PBMC treated with HFI against tumor cells is significantly enhanced. HFI iS effective in mediating ADCC and the activity of HFI-induced ADCC is correlated with the degrees of erbB2 expression on the tumor cells.