What causes your gluten intolerance/antibody reaction to gluten?

Unknown. There is a genetic subgroup of the population that was a higher tendency but it can happen to anyone. Why the immune system decides to react to gluten as if it were a germ is unclear.Why the antibodies it forms decides to attack the intestine or other tissues in some is also unclear, but similar to what occurs in rheumatic fever.
Excellent question. No one knows for sure and it may not be unlike other acquired allergies or sensitivities such as seafood or latex. This disease has yet to be fully understood but tremendous advances are being made as it becomes distinguished from previous confusion with irritable bowel syndrome.