Vitreal superoxide and superoxide dismutase after hemorrhagic injury: the role of invasive cells.

It was previously reported that injection of whole blood or hemoglobin into the rabbit vitreous is followed by two periods of immigration of phagocytic cells. The first period occurs within the first few days, and the second at round 3 weeks after experimental injury. In this report, invasive cells from these two periods after intravitreal hemoglobin injection were tested for their ability to release superoxide anion (O2). Levels of vitreal superoxide dismutase activity were also measured. The data indicate that cells of the second but not the first period of influx release excess O2. The cell-generated free radicals may contribute to vitreal liquefaction, although substantial liquefaction precedes the invasion of the second cell population. Since these cells can traverse adjacent tissues like the retina, they may also contribute by free radical production to the retinal injury that follows hemorrhage.