What Causes High Eosinophil Count?

Yes I ve had two biopsies for eosinophilic esophagitis, the esoinophiliia count came back high. I was sent to an allergist and an autoimmune specialist, multiple allergy tests and blood lab tests were taken. All tests taken came back normal. Except for the vitamin B12 test ( which was high ). Both doctors could not explain why I have such a high eosinophiliic count. Can you please guide me as to what step I should take to obtain an answer? I was put on prednisone for three months. This helped to reduce the high count. IF it s possible I d like an answer as to why this condition exists.