IL-10 production in primary PBMC cultures : an in vitro marker for nickel allergy?

• Nickel (Ni) is one of the most known contact allergens and at present, patch test and clinical history constitute the two cornerstones in the diagnostic procedure. Since the patch test is inherited with in vivo provocation and subjective interpretation of the test result, a non-invasive in vitro method with objective interpretation of the test result has long been searched for. Unfortunately, in vitro diagnosis of Ni- allergy is hampered by the fact that Ni2+ is able to trigger in vitro proliferative responses in lymphocytes from both Ni-allergic and non-allergic subjects. This constitutes a problem when LTT (lymphocyte transformation test), the most frequently used in vitro test as a complement in the diagnosis of contact allergy, is considered for Ni allergy. However, other parameters in the in vitro response might be more useful. In this study, Ni2+-stimulated primary PBMC-cultures derived from Ni-allergic and non-allergic subjects were assessed for IFN-γ, IL-4, IL-10 and IL-17. Also, Ni2+ induced lymphoblasts from such cultures were characterized by their immunophenotype and T-cell receptor Vß-affiliation.We found a significantly higher release of IL-10 in Ni2+ treated cultures from allergic than from non-allergic subjects. The Ni2+-induced lymphoblasts from both groups were predominantly CD4+. Two of the allergic patients (n=5) showed a skewing towards TCR-Vß17, a Vß family earlier associated with Ni-allergy. A significant increase in CD134 and CD23 expression indicated that Ni2+ activates B-cells in vitro. In conclusion, IL-10 seems to be a promising marker for Ni-allergy using primary PBMC cultures. Further, flow cytometric screening of Ni2+ induced lymphoblasts can detect expanded TCR-Vß families that may be used for preparation of Ni-specific T cell clones.

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