Place the tuna in a medium-sized bowl, and flake with a fork. Add all of the remaining ingredients, except the bread and cheese, and stir to mix well.
Arrange the bread slices on a baking pan, and spread about 1/2 cup of the tuna mixture over each slice. Top with 1/4 cup of the cheese.
Place the sandwiches under the broiler, about 4 inches below the heat source. Broil for 1 to 2 minutes, or just until the cheese melts. Serve immediately.