TNF and toxic epidermal necrolysis: In patients with SJS/TEN, TNF-α is prominently expressed in keratinocytes and macrophages in the affected skin, with high concentrations found in serum, blister fluid and skin of patients with SJS/TEN compared with controls.5 Etanercept has been shown to effect a decrease in TNF-α secretion in blister fluid and plasma.6 However, many cytokines and cytotoxic proteins are present at higher concentrations in blister fluid/skin tissue; and it is unclear which proteins are pathogenic, diagnostic and/or markers of disease severity and course.5