Molecular insight into Nickel(II) binding by Her2 specific IgE: a possible mechanistic insight into the pathogenesis of Type I nickel hypersensitivity

Nickel (Ni) allergy has been reported in contact dermatitis Type IV (Ni-specific T cells mediated) and asthmatic Type I (IgE-mediated) hypersensitivities. Associations between the two hypersensitivities have been found in some patients, but the underlying mechanisms remain enigmatic. Using Her2-specific IgEs as models, we found additional binding to Ni-NTA without observable changes in binding to Her2 and that glutamine, together with the canonical Ni2+-binding histidine, could form Ni2+ binding signatures. This mechanism may underlie Type I hypersensitivity in the selection of anti-Ni2+ IgEs. This mechanism may also underlie Type IV hypersensitivity and the interaction of immunoglobulin proteins with other heavy metal ions. Our findings shed light to how Ni hypersensitivities can occur and how they can be avoided in therapeutics design, or even incorporated for biotechnological purification purposes.