 A few preclinical investigations have demonstrated an upregulation of TNF-alpha in patients with CIU. This is in contrast to acute urticaria where TNF-alpha does not appear to play as important of a role in the inflammatory response . This may explain why patients with CIU do not typically respond to usual therapies for acute urticaria. It has been suggested that CIU is an immediate hypersensitivity phenomenon appearing immediately after exposure to an antigen, but the presence of a delayed inflammatory phase is nevertheless observed in this pathology. Soluble factors play a role in this delayed inflammatory phase. Cytokines, including TNF-alpha, are important mediators the pathogenesis of this delayed response. Studies have demonstrated a similar immune profile as that found in patients with rheumatoid arthritis. In one study, cytokines were evaluated in lesional and non-lesional skin of patients with acute urticaria, CIU, delayed pressure urticaria, and cold urticaria. This study demonstrated upregulation of TNF-alpha on endothelial cells and perivascular cells in the dermis. Additionally, TNF-alpha was expressed throughout the epidermis in lesional and non-lesional skin of CIU patients, but not controls. These preclinical investigations support the use of targeted therapy of TNF-alpha in patients with CIU. Therapies directed at modulating the effects of TNF-alpha, including etanercept, may provide effective and safe long-term treatment for patients not responding to anti-histamines alone. 