Anti-ICOS(Bristol Myers Squibb Co.)

ICOS⁺Treg cells exert important immunosuppressive effects in tumor immunity. We adopt a combination approach of ICOS⁺Treg cells depletion with tumor cell vaccine to evaluate anti-tumor immunity in mouse prostate cancer model. Streptavidin (SA)-mGM-CSF surface-modified RM-1 cells were prepared as the vaccine and the mouse subcutaneous prostate tumor model was used to evaluate the immunity. Tumor growth, flow cytometry, immunohistochemistry, immunofluorescence and enzyme linked immunosorbent assay (ELISA) were performed to evaluate the therapeutic effects. Our results demonstrated that SA-mGM-CSF vaccine was prepared successfully and tumor growth was inhibited. The tumor size in the combination group was much smaller than that in the vaccine with IgG mAb group. The portions of dendritic cells, CD8⁺ and CD4⁺T cells in the mice blood and tumor tissues were increased after treatment with vaccine. There were more immune-suppressing Tregs infiltrated into tumor after treatment with tumor cell vaccine, and ICOS blocking could deplete the infiltrated Tregs, and T lymphocytes increased more dramatically in the combination therapy group. The concentrations of interferon-γ were increased in all vaccine group, the concentrations of Interleukin-10 and Interleukin-4 were much lower in the combination group. Our study demonstrated that ICOS blocking could deplete the tumor-infiltrated ICOS⁺Treg cells. Combining GM-CSF surface-modified RM-1 cell vaccine with Anti-ICOS antibody could induce better antitumor immunity than a vaccine alone.

To investigate the influences of anti-ICOS antibody (anti-ICOSAb) on quantity and function of CD4(+);CD25(+);Foxp3(+);Treg cells from lymph and peripheral blood of rats with bronchial asthma.

The mononuclear cells (MNC) from lymph and blood were co-cultured with anti-ICOSAb, and then the percentage of CD4(+);CD25(+);Foxp3(+);Treg cells were analyzed by flow cytometer (FCM) and the levels of IL-10 and TGF-β1 in supernatants were determined by ELISA.

The MNC were collected from lymph and blood at 0, 24 and 48 h after the last challenge, respectively, and the cells were cultured for 96 h in vitro. The percentage of CD4(+);CD25(+);Foxp3(+);Treg cells in the MNC from lymph was significantly higher than that from blood in each group (P<0.05); The percentage of CD4(+);CD25(+);Foxp3(+);Treg cells in the MNC from lymph and blood in asthma group was significantly lower compare with the normal control group (P<0.05); The percentage of CD4(+);CD25(+);Foxp3(+);Treg cells in the MNC from lymph and blood in the anti-ICOSAb group obviously decreased compare with the asthma group (P<0.05). At 0 h after the last challenge, the level of IL-10 in the supernatant of MNC from lymph and blood in the anti-ICOSAb group were significantly lower than that of the control and asthma groups (P<0.05), while there were no significant differences of TGF-β1 expression in the supernatant of MNC from lymph and blood in each group at different time points.

Blocking the ICOS/ICOSL signaling pathway by anti-ICOSAb could exacerbate the deficiency of CD4(+);CD25(+);Foxp3(+);Treg cells from lymph and blood in bronchial asthmatic rat, meanwhile inhibit the CD4(+);CD25(+);Foxp3(+);Treg cells secreting IL-10 at 0 h after the last challenge, but have no significant effect on the secretion of TGF-β1.