CCL2 is overexpressed by FL-MSCs and is involved in monocyte recruitment. (A) CCL2 production in culture supernatants from HD-MSCs (n = 6) and FL-MSCs (n = 9) was quantified by ELISA at the end of P1 and data are normalized by the number of cultured MSCs. **P < .01. (b) CCL2 was quantified in the BM plasma obtained from HDs (n = 31) and FL patients (n = 26, including 23 patients with FL grade 1-2 and 3 patients with FL grade 3a, identified as white triangles). ***P < .001. (C) Migration of purified peripheral blood monocytes in response to HD-MSC and FL-MSC supernatants collected at the end of P1 and specifically depleted or not from CCL2 with magnetic beads. Monocyte migration index is calculated as the number of TOPRO-3^negCD14^pos viable monocytes migrating in response to MSC supernatant divided by their number in response to migration medium. Results represent the mean ± SD from 3 (HD-MSCs) or 4 (FL-MSCs) independent experiments. *P < .05