CHICAGO--(BUSINESS WIRE)--Fitch Ratings has affirmed 12 classes of WAMU Commercial Mortgage Securities Trust commercial mortgage pass-through certificates series 2007-SL2. A detailed list of rating actions follows at the end of this press release. KEY RATING DRIVERS The affirmations are the result of sufficient credit enhancement due to scheduled amortization and paydown. Although credit enhancement is high compared to other mulitborrower transactions, upgrades are not warranted at this time du