MSCs inhibit T-cell activation. (A) Murine MSCs (mMSCs) inhibit T-cell proliferation upon stimulation with anti-CD3 with or without costimulatory trigger, (B) with the encephalitogenic MOG35-55 peptide, and (C) with ConA. (D) A remarkable inhibition is obtained also with the supernatant from MSC cultures at confluence. ▦ indicates T cells stimulated in the absence of MSCs; ▪, T cells treated with 0.25 × 10⁵ MSCs (A-B), increasing doses of MSCs (C), or MSC-derived supernatant (D). ^*P < .05 by Mann-Whitney U test. Error bars indicate SD values. Proliferative responses are expressed as mean counts per minute (CPM) of at least 3 independent experiments. Sups indicates supernatants.