Identification of clonal T cells in the blood of patients with systemic sclerosis: positive correlation with response to photopheresis.

Objectives To search for circulating clonal T-cell populations in patients with systemic sclerosis (SSc), and to determine whether T-cell clonality in the blood predicts therapeutic response to photopheresis. Design Analysis of clonal T-cell receptor γ gene rearrangements before photopheresis treatment and blinded clinical evaluation of cutaneous response to photopheresis in a case series. Setting University hospital setting. Patients Thirteen consecutive patients with SSc. Interventions Photopheresis in 11 patients. Main Outcome Measures Clonality of T cells in the blood before photopheresis and clinical response to photopheresis. Results Screening of blood samples from 13 SSc patients for clonal T-cell receptor γ gene rearrangements revealed a monoclonal T cell population in 6 (46%) of 13 SSc patients. Clinical response to photopheresis in 11 patients was evaluated in a blinded manner using skin severity scores. Clonality of T cells appeared to be associated with a higher chance of response to photopheresis therapy, as 4 (67%) of 6 patients in the clone-positive group vs 1 (20%) of 5 in the clone-negative group experienced a clinically significant response to treatment. Conclusions A high proportion of patients with SSc have detectable expanded clonal T-cell populations in the peripheral blood, and such patients appear more likely to respond to photopheresis.