Fig. 5.

Exposure to hypoxia induces conversion of B lymphoma cells to macrophages. (A) Following exposure to hypoxia (in an incubation chamber with 5% CO₂ and 95% nitrogen) for 16–24 h, the size of some B lymphoma cells (as determined by Giemsa stain), both CA46 and Toledo, was increased markedly (indicated by arrows). Cell morphology of enlarged cells resembled that of monocytes/macrophages with horseshoe-shape nuclei. These cells were immunologically positive for CD68. (B) SSDRB-transduced B lymphoma cells (Toledo) (EGFP⁺ cells) could hardly engulf any red fluorescent beads (microspheres) under both normoxia and hypoxia exposures. In contrast, macrophages isolated from mouse peritoneal cavity could readily ingest red fluorescent microspheres with high efficiency. (C) Phagocytosis percentage (%) of SSDRB-transduced B lymphoma cells (Toledo) under normoxia or hypoxia was determined, respectively, as the percentage of cells positive with more than 2 internalized microspheres. ***Significantly different (P < 0.001). Each experiment was repeated at least 3 times.