Heat oven to 350°F. In large bowl, toss chicken and 1/2 cup of the wing sauce to coat.
Spray two large (14-inch) pizza pans with cooking spray. Arrange half of the tortilla chips on one pizza pan; top with 2 cups of the chicken and 1 1/2 cups of the mozzarella cheese. Repeat on second pizza pan. Bake 8 to 10 minutes or until cheese is melted. Top each pan with celery and blue cheese; drizzle with remaining 1/4 cup wing sauce.
To serve; slide one pan of nachos off onto other pan to make one large mound of nachos. Serve immediately.