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Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.