Interleukin-2 gene has superior antinociceptive effects when delivered intrathecally.

The antinociceptive effect of interleukin-2 gene on rat carrageenan-induced pain was explored using different delivery methods. Intrathecal (i.t.) or plantar s.c. delivery of plasmid harbouring the interleukin-2 gene produced a marked antinociceptive effect, which was maintained up to 6 days; the administration of recombinant human interleukin-2 only had a transitory effect. The antinociceptive effect lasted longer and was more potent when the interleukin-2 gene was administered i.t. than when delivered s.c. The effect of the interleukin-2 gene was related to its protein expression, was dose dependent, and could be potentiated by liposome. The results suggest that the interleukin-2 gene has a good prospect for clinical use.