Accumulation of common T cell clonotypes in the salivary glands of patients with human T lymphotropic virus type I-associated and idiopathic Sjogren's syndrome

To clarify the pathogenesis of human T lymphotropic virus type I (HTLV- I)-associated Sjogren's syndrome (SS), the TCR Vβ gene usage by the infiltrating lymphocytes in the target organ was examined. The Vβ families predominantly used in the labial salivary gland (LSG) from the HTLV-I- seropositive (HTLV-I⁺) SS patients were more restricted than those from the HTLV-I-seronegative (idiopathic) SS patients, and were commonly Vβ5.2, Vβ6, and Vβ7. The single-strand conformation polymorphism analysis revealed that T cell clonotypes with Vβ5.2, Vβ6, and Vβ7 accumulate in the LSG from the HTLV-I⁺ and idiopathic SS patients. Among junctional sequences of the most dominant Vβ7 transcripts, the conserved amino acid motif (QDXG: X is any amino acid) was found in six of the five HTLV-I⁺ SS patients and was also detected in two of the five idiopathic SS patients. Using the probes specific to the motif, the Vβ7 transcripts with the motif were detected in the LSG from all of the seven HTLV-I⁺ and five of the six idiopathic SS patients, but not from eight healthy subjects. The Vβ7 transcripts with this motif were also detected in the HTLV-I-infected T cell lines obtained from the LSG of an HTLV-I⁺ SS patient. The accumulation of HTLV-I-infected T cells expressing TCR with the conserved motif was thus indicated. These T cells were commonly present in patients with idiopathic SS and are strongly suggested to most likely be involved in the pathogenesis of both HTLV-I- associated and idiopathic SS.