Oliigoclonal expansion of Vδ1⁺ γ/δ T-cells in systemic sclerosis patients

Systemic sclerosis (SSc) is a multisystem disease characterized by T-cell infiltration of involved tissues, fibrosis, and small vessel vasculopathy. Using flow cytometric analyses, we found an increased percentage of γ/δ T-cells expressing the T-cell antigen receptor variable (V) δ1 gene segment in the peripheral blood and bronchoalveolar lavage fluid of patients with SSc. To estimate clonality of these Vδ1⁺ T-cells, the diversity of Vδ1 junctional regions (V-Diversity-Joining gene segments) was examined using a reverse transcriptase-polymerase chain reaction to amplify T-cell antigen receptor δ chain transcripts isolated from peripheral blood mononuclear cells, lung, esophagus, stomach, or skin of patients and controls. Limited diversity of Vδ1-Jδ junctional regions in SSc patients was demonstrated by the finding of greater restriction in the nucleotide lengths of junctional region cDNAs in individual SSc patients than in controls. Sequence analyses confirmed that Vδ1-Jδ junctional regions from the blood of SSc patients had less diversity than those from controls, in that a significantly higher proportion of sequences were repeated in patients (54.4% vs. 19.4% in controls). Evidence for selection of the Vδ1⁺ T-cells in tissues of individual SSc patients came from the findings that the same Vδ1-Jδ junctional sequences could be isolated from the same tissue over time and that identical Vδ1-Jδ junctional sequences could be isolated from multiple tissues. These data suggest that expansion of Vδ1⁺ γ/δ T cells may be antigen driven in SSc patients.