Systemic sclerosis (SSc) is a chronic autoimmune disease, characterized by immune system dysregulation, uncontrolled deposition of collagen and microvascular damage in the skin and several internal organs. T cells have a key role in the initiation and propagation of SSc. Our laboratory has previously identified the presence of high proportions of identical α- and β-chains TCR transcripts in skin biopsies from patients with SSc of recent onset, demonstrating clonal expansion of T cells in response to one or more antigens. In order to identify these antigens, pairs of those in vivo clonally expanded α- and β-chain TCR transcripts from two patients with SSc (SSc-21 and SSc-22) were expressed in mutant TCR negative T cells, J.RT3-T3.5, generating a total of 52 T cell lines, including 10 controls. An intracellular Ca2+ mobilization assay was employed to examine whether these transduced Jurkat T cell lines recognize putative SSc antigens presented by autologous EBV-transformed B cell lines. The self-antigen, DNA topoisomerase I and CMV and parvovirus antigens were tested. Statistically significant intracellular Ca2+ mobilization was observed in response to 3 DNA topoisomerase I and 2 CMV peptides by 5 T cell lines expressing clonally expanded α- and β-chain TCR transcripts from patient SSc-21 and SSc-22. These results demonstrate that clonally expanded T cells recognizing DNA topoisomerase I or CMV antigens are present in skin biopsies of recent onset of patients with SSc.

Systemic Sclerosis (SSc) is a chronic autoimmune disease characterized by excessive deposition of collagen in the skin and many internal organs, production of autoantibodies and microvascular alterations. Previous studies in our laboratory have demonstrated the presence of high proportions of identical β-chains TCR transcripts in skin biopsies from patients with SSc of recent onset, suggestive of clonal expansions of T cells. To identify the antigen(s) recognized by clonally expanded T cells in SSc biopsies, we examine the clonality of the α-chain TCR transcripts in patients with SSc. Sequence analysis of α-chain TCR transcripts following non-palindromic PCR/Vα specific PCR and cloning revealed the presence of clonally expanded α-chain TCR transcripts in skin biopsies from four patients with SSc. Substantial proportion of identical α-chain TCR transcripts were found in these skin biopsies accounting from 16% to 32% of the transcripts sequenced. These clonal expansions were confirmed with Vα-specific PCR followed by cloning and sequencing. Identical α-chain TCR transcripts, ranging from 68% to 100%, were identified in individual Vα families. In one of these patients an identical T cell clone was clonally expanded in both peripheral blood and skin. These T cells have undergone clonal expansion in response to, as yet unidentified, specific antigen(s).