Official lobbying disclosures show the company picked up the firm Fierce, Isakowitz and Blalock on Feb. 1 to handle “innovation” issues in Washington. It’s an unexpected expansion for a company that typically keeps a low Washington profile.

The filing offers no further details about specific topics the firm will tackle on Apple’s behalf. Neither the company nor the firm responded to requests for comment Thursday.

Apple may be a heavyweight in Silicon Valley, but the company tends to fly below the radar in D.C. The iPhone maker is regularly outspent by many of its top competitors — including Microsoft, which shelled out almost $7 million to canvass the Capitol on top tech issues 2010. Apple, meanwhile, spent just over $1.6 million on lobbying over the same period.

Apple has received scrutiny from regulators, who have eyed its App Store guidelines and its handling of Flash video on the iPhone. At the same time, Capitol Hill has ramped up debate over issues such as online privacy and competitiveness – topics that could affect Apple’s bottom line.

Apple’s 2010 lobbying forms reflect the company has been an active participant in those conversations, speaking to lawmakers and federal regulators about patents, research funding, free trade agreements and taxes. It’s new outside firm, Fierce, Isakowitz and Blalock, has handled some of those issues for other industry clients such as CTIA, the National Cable and Telecommunications Association, Time Warner Cable and the Coalition for Patent Fairness.

Among the lobbyists handling Apple’s work is firm president Mark Isakowitz, who previously headed up federal relations for the National Federation of Independent Business. Isakowitz’s resume also includes work on former President George W. Bush’s transition team, and time spent as press secretary for Rep. Paul Gilmor (R-Ohio), a former top member of the House Commerce Committee.

Also on the team is Kirk Blalock, a firm partner who previously served under Bush as a special assistant and deputy director of the Office of Public Liaison. Kristen Chadwick, another lobbyist listed on the filing, previously served as a special assistant on legislative affairs for Bush until 2004.