Mycoplasma Contamination Revisited: Mesenchymal Stromal Cells Harboring Mycoplasma hyorhinis Potently Inhibit Lymphocyte Proliferation In Vitro
Figure 2
MLR is inhibited by MSC culture supernatant.
Inhibition of lymphocyte proliferation was reversed either by (A) filtration at 0.22 µm, (B) serial centrifugation at 100 000 g, or (C) heat-treatment at 60°C. (A) MSC-conditioned supernatant (MSC-sn; gray bars) was added at 1∶10 (v/v) dilution (22 µL added to 200 µL per well) at the start of mitogenic stimulation of 2×105 PVG.7B LNC with Con A (positive control with no MSC-sn added, black bar). MSC-sn was added either unfiltered or filtered with the indicated cut-off sizes. (B) MSC-sn was sedimented with the indicated centrifugal forces and durations (min) and added at 1∶10 (v/v) dilution at the start of allogeneic MLR (cf. Figure 1). The pellet fraction (MSC-pt) was obtained after centrifugation twice for 60 min at 100 000 g, resuspended and added at 1∶10 (v/v) dilution to the MLR. (C) Unprocessed MSC-sn or the resuspended pellet fraction described in panel B were treated at 30°C (light gray bars) and 60°C (dark gray) for 30 min, respectively, before adding to MLR (dilution 1∶10). Representative data of at least two independent experiments are shown as mean values plus the standard error of the mean of quadruplicates. Statistical difference to the respective positive controls, •• P<.01, ••• P<.001.