Kahnle was optioned to Triple-A Charlotte on Monday, Daryl Van Schouwen of the Chicago Sun-Times reports.
Kahnle has allowed just one earned run in four appearances with the White Sox this season, but he was sent down Monday to open up a roster spot for outfielder J.B. Shuck. Kahnle has already had two stints with the big club this season, so he will garner consideration next time the White Sox need to bring up a reliever.