Heat oven to 375°F. Bake biscuits as directed on can. Cool slightly. Split; arrange, cut side up, on same cookie sheet.
Meanwhile, in medium bowl, combine tuna, celery, pineapple, onion and salad dressing; mix well.
Spoon mixture evenly onto split biscuits. Cut cheese slices in half diagonally; place 1 piece on each topped biscuit half.
Bake for 5 to 7 minutes or until filling is hot and cheese is melted.