Cytokine Production, Lymphocyte Proliferation and T-Cell Receptor Vβ Expression in Primary Peripheral Blood Mononuclear Cell Cultures from Nickel-Allergic Individuals

Abstract

Background: Clinical history and patch test constitute the two cornerstones in the diagnosis of nickel (Ni) allergy. Due to technical and interpretative limits of the patch test, the in vitro lymphocyte transformation test (LTT) has been developed for confirming contact allergy; however, most studies show an overlap in lymphocyte proliferation between Ni-allergic and nonallergic subjects using the LTT. The aim of this study was to see if the secretion of cytokines, especially interleukin (IL)-10 and IL-17, or the use of T-cell receptor (TCR) Vβ families in Ni-stimulated primary peripheral blood mononuclear cell (PBMC) cultures might be more useful for discriminating between allergic and nonallergic subjects. Methods: Ni²⁺-stimulated primary PBMC cultures derived from female subjects diagnosed as Ni-allergic (n = 5) or nonallergic (n = 5) on the basis of a positive or negative patch test were assessed for cell proliferation by tritiated thymidine incorporation and for production of interferon-γ, IL-4, IL-10 and IL-17 in the culture supernatant by ELISA. The immunophenotype and TCR-Vβ family affiliation of the Ni²⁺-induced lymphoblasts were determined by flow cytometry. Results: Lymphocytes from Ni-allergic individuals challenged with a high and a low concentration of Ni showed significantly higher cell proliferation than lymphocytes from nonallergic individuals, but all subjects showed a positive LTT result (stimulation index >2). We found a significantly higher release of IL-10 in Ni²⁺-treated cultures from Ni-allergic compared with nonallergic subjects that provided better separation between individuals in the two groups than did lymphocyte proliferation. The proliferating lymphoblasts were predominantly CD4+, and in 2 of the 5 Ni-allergic subjects, but in none of the 5 nonallergic subjects, the CD4+ lymphoblasts showed a dominance of TCR-Vβ17. Conclusions: Determination of IL-10 production in primary PBMC cultures is a potentially promising in vitro method for discrimination of Ni allergy in females, as compared with cell proliferation.