Analysis of nickel-binding proteins in human T cells

Nickel (Ni) represents the most common contact allergen in humans. In this study, HLA-restricted Ni-reactive T cell clones were induced from peripheral blood lymphocytes of Ni-allergic donors, either with Ni-salts, with Ni complexed to human serum albumin (HSA-Ni) or to modified horseradish peroxidase (Ni-POD). To elucidate molecular mechanisms underlying Ni-induced T cell activation we investigated binding of Ni-POD to cells. As shown by FACS analysis the reagent binds Ni-specifically to cell surfaces including human T cells. We are presently enriching cellular proteins, which have been bound to Ni-NTA-agarose. These proteins are being studied by 2-D electrophoresis, peptide mass fingerprinting, MALDI- and ESI-MS analysis. The identification of Ni-binding proteins might help to clarify the molecular processes involved in Ni-specific T cell activation in allergic contact dermatitis.