Harrison left practice on Wednesday last week, missed Thursday's and Friday's sessions, keeping him out of the season-opener at Denver.
Strong safety Troy Polamalu is nursing a heel injury, and was kept out of action as well. He isn't expected to miss Sunday's game, but any injury that would directly result in a loss of speed and quickness is an injury of some significance, even if he is able to play.
Previously unreported, running back Jonathan Dwyer sat out Wednesday's practice with a foot injury. Dwyer carried the ball nine times in the loss against Denver for a team-high 43 yards on nine carries, and looks to be more involved in the game plan in Week 2.
Defensive end Ziggy Hood was limited Wednesday with a back injury.
Interestingly, RB Rashard Mendenhall practiced fully again, continuing his streak of perfect attendance at practice this season. Mendenhall wasn't active in Week 1, and isn't likely to be active against the Jets. The more he can practice, though, the stronger he'll be upon his return, which is likely targeted around Week 5 - a week after the Steelers' bye.
LB Stevenson Sylvester missed Wednesday's session, and could miss his second consecutive game as he continues to recover from a preseason knee injury.