Wash the celery, cut off the leaves and remove outside stalks.
Carefully separate the stalks and keep in order, as they will be put together again.
Beat the cheese, buttermilk and salt until smooth.
Blend in the chives and pimentos.
Spread in the hollows of the celery and rebuild stalk.
Wrap firmly in waxed paper or aluminum foil and chill 2 hours.
Cut in 1/2-inch slices.