IL18 and microtia: As a new type of chemotactic regulator with multiple biological activities, IL-18 can regulate the balance of T helper cell 1/T helper cell 2 (Th1/Th2) bidirectionally, and its overexpression can stimulate the increase of Th1 cells in cooperation with other inflammatory factors, shifting the Th1/Th2 balance toward Th1 and leading to the development of MA [24].