Impaired responses of peripheral blood mononuclear cells to nickel in patients with nickel-allergic contact dermatitis and concomitant atopic dermatitis.

BACKGROUND: Allergic contact dermatitis (ACD) is pathogenetically dependent on cell-mediated immune responses mediated by type 1 T lymphocytes. Atopic dermatitis (AD), in contrast, occurs as a result of sustained activation of type 2 subsets of T cells. Although atopic patients may become sensitized to various contact allergens, little is known about the influence of atopy on delayed-type hypersensitivity.

OBJECTIVES: To investigate the in vitro responses of peripheral blood mononuclear cells (PBMC) to nickel stimulation in groups of atopic and nonatopic patients with patch test-verified nickel ACD.

METHODS: Ten nonatopic patients with nickel ACD, 10 patients with nickel ACD and concomitant AD, 10 patients with AD but with no contact allergy, and 10 healthy persons participated in the study. PBMC were cultured in the presence or absence of nickel sulphate, phytohaemagglutinin (PHA) or tetanus toxoid (TT). [(3)H]thymidine incorporation was used to measure the rate of antigen-induced DNA synthesis and enzyme-linked immunosorbent assay was used to measure the production of interleukin (IL)-2 (type 1 cytokine) and IL-5 (type 2 cytokine).

RESULTS: Nickel-stimulated PBMC of nickel-allergic patients with AD proliferated significantly less and secreted significantly lower amounts of IL-2 than cells of nonatopic nickel-allergic patients. IL-5 production was also lower in the former group, although the difference was nonsignificant. Moreover, neither the nickel-specific DNA synthesis nor the cytokine production by PBMC of atopic nickel-allergic patients differed significantly from those of healthy control persons and AD patients without contact allergy. Proliferative and secretory responses of PBMC to PHA or TT stimulation differed nonsignificantly between the groups. Nickel-induced IL-2 production correlated well with IL-5 production in nickel-allergic patients regardless of their atopic status.

CONCLUSIONS: Our results indicate that PBMC of nickel-allergic patients with concomitant AD are characterized by impaired in vitro proliferative and secretory responses to the contact allergen nickel but not to the mitogen PHA or the recall antigen TT. The type 2 cytokine IL-5 may play a role in the development of ACD.