Iontophoresis of nickel elicits a delayed cutaneous response in sensitizedindividuals that is similar to an allergic patch test reaction

Wearing of patch test chambers for 1-2 days is uncomfortable for patients. Allergen application by iontophoresis avoids this, but it is unknown so far whether iontophoresis itself interferes with the delayed immune response. We compared the effects occurring 48 h after iontophoresis with distilled w ater, 0.9% NaCl, and 0.01 M NiSO4 in normal volunteers and in nickel-sensit ized patients (total n=36). Visual assessment was performed and transepider mal water loss (TEWL), stratum corneum hydration, cutaneous blood how and i mmunohistopathology were determined. After iontophoresis with nickel sulfat e, only individuals sensitized to nickel reacted with a positive clinical r esponse, increase in cutaneous blood how decline in epidermal CD-1a-positiv e cells, increase in epidermal proliferation (Ki-67-positive cells), pronou nced infiltration of cells positive for CD4, CD11, or CLA, and cellular act ivation (expression of ICAM1, HLA-DR). Iontophoresis with distilled water o r saline did not result in such reactions in volunteers with or without nic kel sensitization, and the latter also tolerated nickel iontophoresis witho ut significant skin reactions. We conclude that the delayed cutaneous respo nse to nickel induced via iontophoresis is specific and similar to a positi ve patch test reaction. Iontophoresis may therefore be considered as an alt ernative to patch testing.