CONTACT HYPERSENSITIVITY TO DISODIUM HEXACHLOROPLATINATE IN MICE

Complex platinum (Pt) compounds are known as occupational respiratory sensitizers whereas their role in skin exposure is unclear. In this st udy, both skin irritation and induction of contact hypersensitivity by halide Pt salts were characterized in mice. Repeated application of N a-2[PtCl6] (5% in acetone) to both ears of naive BALB/c mice induced a ctivation of the draining auricular lymph nodes. Flow cytometric analy sis revealed a striking increase in the number of lymph node cells exp ressing proliferating cell nuclear antigen. In separate experiments, N a-2[PtCl6] or acetone were applied only to the right ear of mice on 4- 8 consecutive days and the animals were challenged on the left ear 6 d ays later. Ear thickness was determined before and 0.5, 24, 48, and 72 h after challenge with 0.5 or 2% Na-2[PtCl6] or acetone. Maximal swel ling of the left ear was recorded at 48 h in Pt-sensitized mice challe nged with 2% Na-2[PtCl6]. Furthermore, the concentration of Na-2[PtCl6 ] required for sensitization caused an irritant reaction as demonstrat ed by significant swelling of the right ear. These data support the co ncept that both irritant and allergic contact dermatitis to halide Pt salts may occur in humans. Concerning skin exposure to halide Pt salts , Pt-induced irritant reactions resulting from an intrinsic adjuvant's activity of the compound could be a prerequisite for sensitization. ( C) 1997 Elsevier Science Ireland Ltd.