Not on the latest two IEEE 802.3bt power standards. Type 3 (60w) can use all four pair and Type 4 (100w) has to use all four pair. Those are the only two standards that make sense for PoE lighting as a solution.
I think all versions of PoE allowed for power and data on the same pairs. It was only in the versions where only 2 pairs are used for data (10BaseT, 100BaseT) and only 2 pairs are used for power (the power levels called Type 1 and Type 2 under the latest standard) that it was possible to separate the power and data pairs. Possible, but not required.
