dermatologic disorders
Stevens Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)
Pathophysiology of SJS and TEN
The exact mechanism of Stevens-Johnson syndrome and toxic epidermal necrolysis is unknown; however, one theory holds that altered drug metabolism (eg, failure to clear reactive metabolites) in some patients triggers a T-cell–mediated cytotoxic reaction to drug antigens in keratinocytes. CD8+ T cells have been identified as important mediators of blister formation. Findings suggest that granulysin released from cytotoxic T cells and natural killer cells might play a role in keratinocyte death; granulysin concentration in blister fluid correlates with severity of disease. Interleukin-15 has also been found to be increased in patients with SJS/TEN and has been found to increase granulysin production. Another theory is that interactions between Fas (a cell-surface receptor that induces apoptosis) and its ligand, particularly a soluble form of Fas ligand released from mononuclear cells, lead to cell death and blister formation. A genetic predisposition for SJS/TEN has been suggested. 