Conditioned medium from MIP-101 and CX-1 cells or HuT 78 fails to protect against anti-Fas–mediated apoptosis or induce apoptosis, respectively. Serum-free medium conditioned by MIP-101, CX-1, or HuT 78 cells was depleted of extracellular vesicles by sequential centrifugation at 800g for 30 minutes and at 100,000g at 8°C for 12 hours. Negative and positive controls were established by treating 2 × 105 CX-1 cells with 100 ng noncytotoxic, isotype-matched IgM (IsoAb), or antihuman Fas IgM (anti-Fas), respectively. (A) CX-1 cells were treated with 100 ng antihuman Fas Ab and 100 μL medium conditioned by CX-1 (CX-1) or MIP-101 (MIP-101) cells, respectively. Note that CX-1 and MIP-101 cell-conditioned medium fails to protect CX-1 cells from anti-Fas–induced cell death. (B) Positive and negative controls were established, as described above. CX-1 cells were treated 100 μL HuT 78 conditioned medium (HuT 78). Note that HuT 78 cell-conditioned medium fails to induce apoptosis of CX-1 cells. Shown are the mean ± SD values in three separate experiments.
