Follow-up of the T-cell clonality in Sezary patients treated by extracorporeal photopheresis using a new assay: the immunoscope technique

Sezary syndrome is a leukemic form of epidermotropic cutaneous T-cell lymphoma related to the malignant proliferation of clonal CD4+ T-cells. Extracorporeal photochemotherapy (ECP) may induce a transient improvement of the clinical signs but it’s efficiency is discussed. In order to investigate the T-cell clonality in the peripheral blood of patients with Sezary syndrome and to monitor its evolution in 8 patients treated by ECP, we used the Immunoscope technique. In one patient, we observed a decrease of the T-cell clonality from 15.6% to 0%, paralleling a complete remission of the clinical disease with a disappearance of the circulating Sezary cells. In the other cases, the evolution of the relative frequency paralleled the clinical status of the patient. In 3 cases, we observed a quick-acting direct cytotoxicity of the association 8MOP+UVA on the T-cell clone present in the cellular product. Immunoscope technique appears to be an efficient assay to appreciate the amount of tumoral cells and monitor the evolution of the clonal component in Sezary syndrome.