Figure 5.

Polarization of Siglec-7 and inhibition of Siglec-7⁺ CD8+ T cells induced by sialoglycans on tumor cells. (A–F) Confocal immunofluorescence microscopy analysis of immunological synapse (IS) formation between redirected CD8+ T cell subsets and αCD3 mAb-loaded P815 tumor cells in absence or presence of target cell neuraminidase treatment (NT). Representative images (A, C) and corresponding fluorescence profiles plotted along the indicated trajectory (B, D). Quantification of Siglec-7 polarization on T cells towards the IS (E), or actin staining intensity at the synapse (F), compared with the opposite side of the same T cell. (G–I) Effects of neuraminidase pre-treatment of P815 target cells on redirected cytotoxicity (G) and intracellular IFN-γ (H) or TNF−α (I) production 4 h after target cell loading with αCD3 mAb (n=5). (A–F) analysis of at least 40 conjugates from three independent experiments with cells from at least three donors. Statistical analyses were performed by paired t test (E–G) or one-way ANOVA followed by Bonferroni posttest (H, I). *P < 0.05; **P < 0.01. Error bars, SD.