IL4 and Alzheimer disease: AD is a Th2-mediated disease, involving both IL-4 and IL-13.1, 3, 5, 6 IL-4 was considered the pivotal cytokine, but recent studies showed overexpression of IL-13 in lesional skin, particularly in the chronic stage, with a correlation between its tissue levels and disease severity, suggesting a preponderant role in the underlying inflammation.1, 5, 6 In contrast, IL-4 levels were almost undetectable.