To investigate the mechanisms underlying the expression of allergic contact dermatitis, we compared the characteristics of nickel (Ni)-specific T cell responses in 10 patients with allergic contact dermatitis to Ni and in 10 healthy, nonallergic individuals. CD4+ T cells purified from peripheral blood of both allergic and nonallergic subjects proliferated similarly to NiSO4 in vitro, with the responses mostly restricted to CD4+ CD45RO+ memory T cells. In contrast, Ni-specific CD8+ T cell responses were detected only in allergic patients. Limiting dilution assay confirmed a high frequency of Ni-specific CD4+ T cells in both individual categories, and of Ni-specific CD8+ T cells in allergic patients, but not in nonallergic persons. Ni-specific CD4+ T cell clones prepared from nonallergic subjects displayed lower interferon-gamma and higher interleukin-10 production compared with T cell clones from allergic patients. The T cell skin-homing receptor, cutaneous lymphocyte-associated antigen, was expressed on the large majority of specific CD4+ clones from both the groups. Finally, Ni-specific CD8+ clones prepared from patients also expressed the cutaneous lymphocyte-associated antigen receptor, and released high interferon-gamma and no interleukin-4. In aggregate, the results suggest that the presence of specific CD8+ T cells and a distinct pattern of cytokine release (e.g., an augmented production of interleukin-10) by CD4+ T cells can be important elements in determining whether a hapten induces allergy or a silent immune response.

Testing IgE reactivity to a panel of nsLTP allergens unveils important associations between nsLTP sensitization profiles and clinical presentation and allows the identification of novel cluster patterns indicating likely cross-reactivities and highlighting potential allergens for nsLTP immunotherapy.

Poor or no biological activity and lack of clinical relevance of IgE-binding plant glycans (five out of five) was demonstrated using human lactoferrin expressed in rice as a model.

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Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the US government. Disclosure of potential conflict of interest: M. G. Lawrence has received consultancy fees from Baxter as a member of the Advisory Board. J. W. Leiding has received consultancy fees from the Academy for Continued Healthcare Learning; has received research support from the American Academy of Allergy, Asthma & Immunology ARTrust, All Children's Hospital Foundation; and has received lecture fees from Vidara Therapeutics and Immunodeficiency Foundation. T. A. Platts-Mills has received research support from Thermo-Fisher/Phadia. The rest of the authors declare that they have no relevant conflicts of interest.