Immunophenotyping of the eczematous flare-up reaction in a nickel-sensitive subject.

An eczematous flare-up reaction, occurring at a previously involved site, which followed oral challenge with 5.6 mg of nickel in a 29-year-old nickel-sensitive woman, was biopsied and studied by immunohistochemistry. The cellular infiltrate in the dermis and epidermis at 8 days was predominantly of Leu 3a phenotype (helper/inducer T lymphocytes), with smaller numbers of Leu-2a-reactive (suppressor/cytotoxic) T lymphocytes. Many infiltrating cells were DR-positive. No increase in epidermal Leu-6-positive Langerhans cells was seen but Leu-6-reactive cells were noted in the dermal infiltrate. Keratinocytes showed some expression of class II antigen (mainly DR). In comparison with the 48-hour allergic patch test reaction, the eczematous flare-up site showed no increase in epidermal Langerhans cell numbers nor infiltration with macrophages, but the responses were similar since both showed a superficial T cell reaction in the skin.