Final answer:
Eosinophils are the most likely cell type to be increased in a patient experiencing severe, persistent allergy symptoms. They are involved in allergic reactions and release proinflammatory compounds.
Step-by-step explanation:
An elevated activity of eosinophils is likely to be increased in a patient experiencing severe, persistent allergy symptoms. Eosinophils are white blood cells that are involved in allergic reactions and target parasitic infections. They release histamine and other proinflammatory compounds from their granules upon stimulation, which can cause symptoms such as sneezing, rhinorrhea, and watery eyes.