Molecular analysis of T-cell clonality with concomitant specific T-cell proliferation in vitro in nickel-allergic individuals

Background: The peripheral blood mononuclear cells (PBMC) of individuals with nickel contact allergy are reported to proliferate to a varying degree upon nickel stimulation in vitro. Different phenotypes of the T cells involved are described. With regard to preferential use of the T-cell receptor (TCR), analysis of the several families of the TCR-γ gene allows rearrangement evaluation of all T cells regardless of predominant surface expression of TCR α/β. Methods: The PBMC of 10 nickel-allergic and five nonallergic individuals were cultured for 4 days in the presence of either medium, PHA, NiSO4, or tetanus toxoid (TT). Proliferation was measured by radioactive thymidine uptake and expressed as stimulation index (SI). T-cell clonality was assessed by analysis of the TCR-γ chain gene, including the use of PCR with a primer combination covering the four main groups (Vγ1-8, Vγ9, Vγ10, and Vγ11) of the variable region of the TCR-β chain gene. Results: In the allergic individuals, proliferation to NiSO4 was significantly (P