Identification of an interleukin 2-like substance as a factor cytotoxic to oligodendrocytes and associated with central nervous system regeneration.

Axons of the central nervous system in adult mammals do not regenerate spontaneously after injury, partly because of the presence of oligodendrocytes that inhibit axonal growth. This is not the case in lower vertebrates (e.g., in fish), where regeneration of the optic nerve does occur spontaneously and has been correlated with the presence of factors cytotoxic to oligodendrocytes. The present study provides evidence that the substance originating from the fish optic nerves, which is cytotoxic to oligodendrocytes, is an interleukin 2-like substance.