Figure 4.

TNC inhibits T cell functions through integrin α5β1 and αvβ6. (a) Live/dead cell FACS analysis shows that TNC is not toxic to activated T cells after 2 days incubation. (b) Huaman T cells were activated with anti-CD3 and anti-CD28 antibodies in the presence of exogenous TNC and blocking antibodies to α2β1, α5β1, α9β1 and αvβ6 integrin receptor. Blocking antibodies to α5β1and αvβ6 abrogated the suppressive activity of TNC on T cell proliferation. (c) Combination of blocking antibodies to α5β1 and αvβ6 had a greater effect on the reversion of T cell proliferation that either antibody alone. (d) Activated T cells express α5β1and αvβ6 receptor as documented by flow cytometry analysis. (e, f) Purified TNC reduced the expression of p-Akt (MFI) and p-mTOR (% cells and MFI). (g) Down-regulation of p-mTOR and total mTOR in T cells after treatment with BT025 CM and TNC. (h) Blocking both α5β1and αvβ6 receptors following treatment with TNC elevated p-mTOR expression in T cells.

All bars are mean ± SEM of triplicate cultures. Data in all panels are analyzed by 1-way ANOVA with Tukey’s multiple comparisons post-hoc test. *P < 0.05, **P < 10^–2, ***P < 10^–3, ****P < 10^–4 compared to ACT group (p values in panel b, c and h are relative to ACT+TNC group unless otherwise displayed). ACT, activated T cell; NAT, non-activated T cell.