Studies on the expression of IL-18 and its antagonist, IL-18 Binding Protein (IL-18BP), using a coculture model demonstrated severe IL-18⁄IL-18BP imbalance in keloid keratinocyte/keloid fibroblast cocultures with significant elevation of bioactive IL-18 whereas IL-18BP levels remained the same. The gene discussed is IL18BP; the disease is keloid.