Galectin-1 contributes to the antiproliferative effects of MSCs against alloreactive T cells but not against NK cells. (A-D) Analysis of proliferation of CD4⁺ T cells (A,C) and CD8⁺ T cells (B,D) in the presence of MSCs; MSC^G1▾ showed strongly reduced antiproliferative effects compared with MSC^wt or MSC^contr. This was independent of the T-cell stimulus; the T cells were either simulated by αCD28/OKT3 (A,B), or they were stimulated by a mixed lymphocyte reaction (C-D). (E) Proliferation of CD56⁺ NK cells in the absence or presence of MSCs. Suppression of NK cell proliferation in response to IL-2 was comparable when MSC^G1▾, MSC^wt, or MSC^contr were present. Data in all panels are shown as means (± SD) of quadruplicates (n = 3).