Jackson was held out of Wednesday's camp session due to a right knee sprain, Ben Baby of ESPN.com reports.
Jackson told Kelsey Conway of The Cincinnati Enquirer that he's considered day-to-day after Wednesday's practice, but his knee was in a brace and he had crutches next to his locker, which doesn't seem like a good sign. Once Jackson returns to full health, he's expected to continue competing for a depth spot on the Bengals' defensive line.