IL18 and atopic eczema: In addition, IL-18 expression is also increased in human atopic eczema, possibly via the upregulation of the T helper 1 (Th1) immune response and downregulation of the T helper 2 (Th2) immune response, which aggravates the imbalance between Th1 and Th2 cells and results in the deterioration etiology of atopic eczema seen in humans [8, 9].