TCRs with segment TRAV9‐2 or a CDR3 histidine are overrepresented among nickel‐specific CD4+ T cells
Marina Aparicio‐Soto, Franziska Riedel, Melanie Leddermann, Petra Bächer, Alexander Scheffold, Heiner Kuhl, Bernd Timmermann, Dmitriy M. Chudakov, Sonja Molin, Margitta Worm, Guido Heine, Hermann‐Josef Thierse, Andreas Luch, Katherina Siewert
Abstract
Abstract Background Nickel is the most frequent cause of T cell–mediated allergic contact dermatitis worldwide. In vitro, CD4+ T cells from all donors respond to nickel but the involved αβ T cell receptor (TCR) repertoire has not been comprehensively analyzed. Methods We introduce CD154 (CD40L) upregulation as a fast, unbiased, and quantitative method to detect nickel‐specific CD4+ T cells ex vivo in blood of clinically characterized allergic and non allergic donors. Naïve (CCR7+ CD45RA+) and memory (not naïve) CD154+ CD4+ T cells were analyzed by flow cytometry after 5 hours of stimulation with 200 µmol/L NiSO 4 ., TCR α‐ and β‐chains of sorted nickel‐specific and control cells were studied by high‐throughput sequencing. Results Stimulation of PBMCs with NiSO 4 induced CD154 expression on ~0.1% (mean) of naïve and memory CD4+ T cells. In allergic donors with recent positive patch test, memory frequencies further increased ~13‐fold and were associated with markers of in vivo activation. CD154 expression was TCR‐mediated since single clones could be specifically restimulated. Among nickel‐specific CD4+ T cells of allergic and non allergic donors, TCRs expressing the α‐chain segment TRAV9‐2 or a histidine in their α‐ or β‐chain complementarity determining region 3 (CDR3) were highly overrepresented. Conclusions Induced CD154 expression represents a reliable method to study nickel‐specific CD4+ T cells. TCRs with particular features respond in all donors, while strongly increased blood frequencies indicate nickel allergy for some donors. Our approach may be extended to other contact allergens for the further development of diagnostic and predictive in vitro tests.