Analysis of T-cell antigen receptor variable region gene usage in patients with thyroid-related pretibial dermopathy

It is unknown whether T cells infiltrating the pretibial skin of patients with thyroid-related pretibial dermopathy represent a primary immune response or participate in a nonspecific inflammatory process. To characterize these T cells at the molecular level, we examined the T-cell antigen receptor variable region gene usage in pretibial skin biopsy specimens obtained from patients with early and late stages of pretibial dermopathy and from individuals with unrelated inflammatory conditions of the pretibial skin. RNA extracted from pretibial biopsy specimens and peripheral blood lymphocytes was reverse transcribed and amplified with the polymerase chain reaction and 22 Vα and 23 Vβ gene-specific oligonucleotide primers. The resulting T-cell receptor (TcR) Vα and Vβ transcripts were verified by Southern hybridization analysis using TcR C-region-specific, digoxigenin-labeled oligonucleotide probes. Compared with matched peripheral blood lymphocytes, the pretibial TcR Vα and Vβ gene repertoire expressed was heterogeneous but revealed marked restriction of Vα and Vβ gene usage in samples derived from patients with active inflammatory pretibial dermopathy of recent onset. In contrast, greater diversity of the TcR Vα gene repertoire and loss of TcR Vβ gene restriction were noted in patients with longstanding, clinically inactive pretibial dermopathy. TcR V gene usage in pretibial tissue and peripheral blood lymphocyte samples obtained from control subjects was unrestricted. Limited variability of TcR V gene usage in early pretibial dermopathy may reflect a primary immune response of antigen-specific T lymphocytes infiltrating the pretibial skin in thyroid-related pretibial dermopathy.