There are three main types of AD animal models: The first category consists of hapten-induced models, which use repeated applications of haptens [oxazolone, DNCB (2,4-dinitrochlorobenzene)] to induce a transition from delayed-type hypersensitivity to Th2-dominated chronic inflammation, characterized by elevated levels of Th2-associated cytokines, including IL-4, IL-5, and IL-13. This evidence concerns the gene IL4 and Alzheimer disease.