A strong positive, allergic patch-test reaction was elicited in 15 patients with an established allergy for a particular allergen. Patches with a marginally irritating concentration of sodium lauryl sulfate (SLS) were applied at fixed distances. The SLS patch situated adjacent to the allergic reaction was significantly enhanced in 12 of 15 patients (
P<0.01) compared="" to="" more="" distant="" sls="" reactions="">
spillover
). Only quantitative differences were observed in the histologic pictures of the different types of reaction. The infiltrate consisted of lymphocytes and histiocytes, mainly located perivascular in the upper dermis.
T-cell subsets were assessed with monoclonal antibodies using an immunoperoxidase technique. The distribution of the different T cells was the same for both reaction types.
T cells located outside the perivascular infiltrates (e.g., in the epidermal vesicles) were OKT-8-positive (cytotoxic/suppressor T lymphocytes). Immunofluorescence examination did not show different patterns for the allergic or
enhanced toxic
reactions with regard to the presence of immunoglobulins and complement.
The
spillover
phenomenon may cause falsepositive patch-test reactions.
Key words Spillover - T-cell subsets - Monoclonal antibodies - Immunoperoxidase - Immunofluorescence techniques - Allergic, toxic patch-test reactions