To date, it has remained unclear whether orbit-infiltrating T cells in patients with Graves' ophthalmopathy (GO) represent a primary immune response in which a limited number of T cell clones driving the disease are activated against specific antigens, or whether they participate in a non-specific inflammatory process. To characterize these T cells at the molecular level, we examined the T cell antigen receptor (TcR) V gene repertoire in situ in retroorbital tissue specimens obtained from patients with early and late stages of clinically severe GO and from patients with non-GO orbital conditions. Ribonucleic acid extracted from orbital tissue and peripheral blood lymphocytes (PBL) was reverse transcribed and amplified using the polymerase chain reaction and 22 Vα and 24 Vβ gene-specific oligonucleotide primers. The resulting TcR Vα and Vβ transcripts were verified by Southern hybridization analysis using TcR C region-specific, digoxigenin-labeled oligonucleotide probes. Compared with matched PBL, the retroorbital TcR Va and Vβ gene repertoire expressed was heterogeneous, but revealed marked restriction of V gene usage in samples derived from retroorbital connective tissue and extraocular muscle of all eight patients with severe GO of short duration studied. In contrast, greater diversity of the TcR Vβ gene repertoire and loss of TcR Vα gene restriction was noted in four patients with late GO undergoing reconstructive eye muscle surgery. Unrestricted TcR V gene usage was demonstrated in orbital tissue and PBL samples obtained from control subjects. These results suggest that retroorbital TcR V gene usage is variable but markedly restricted during the earlier stages of GO. With increasing disease duration, greater diversity of the TcR V gene repertoire appears to develop, and oligoclonality of the T cell response may be lost. Selection of patients with early stages of GO will be important when further dissecting TcR usage and antigen specificity of orbit-infiltrating T lymphocytes in GO.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism