Cell-cell contact is not required to achieve inhibition of T-cell proliferation.

T lymphocytes and DCs were cultured in the transwell plates to avoid cell-cell contact with BMSCs. Under this culture condition, a significant inhibition (70% ± 5%) of T-cell proliferation was observed which suggested that a soluble factor(s) may be involved in BMSC-induced suppression of T-cell proliferation. In fact, inhibition of T-cell proliferation obtained in standard culture allowing cell-cell contact was significantly higher as compared with that observed in the transwell system. Data are expressed as mean ± SD of triplicates of 3 separate experiments. *Statistically significant when compared with MLRs performed in the transwell in the presence of BMSCs. **Statistically significant when compared with MLRs performed in the presence of BMSCs without transwell.