TNF and Behcet disease: An explanation for the novel association of BD with the IL-18RAP/rs2058660 gene polymorphism could not yet be supported by functional assays with PBMCs, although a recent report did show that this polymorphism was linked to a low expression of the β-chain of this factor, causing a lower response to IL-18, as detected both on the RNA and protein level of CCL3, CCL20, TNF-α and CXCL8 in granulocytes29.