A Long-Term Study of Persistent Sézary Syndrome: Evidence for Antigen Shift by Multiparameter Flow Cytometry and Its Significance in Overall Survival.

Sézary syndrome (SS) is a peripheral T-cell lymphoma characterized by erythroderma, diffuse lymphadenopathy, and circulating neoplastic T cells, which classically show a helper T-cell immunophenotype with loss of CD7 and CD26. Flow cytometry is often used to identify and enumerate populations of Sézary cells in the peripheral blood; however, the significance and frequency of antigen shift over time is unclear. In this article, we follow the immunophenotype of the neoplastic T-cell population from 28 patients with SS across 415 flow cytometry studies. Antigen shift for each patient was assigned as none, minimal = 1-2 markers by 1°, moderate = up to 3 markers, or marked ≥ 4 markers. Sixty-four percent (18/28) of patients showed antigen shift, and among those with antigen shift, the majority showed minimal (8/18) or moderate antigen shift (7/18) with fewer demonstrating marked shift (3/18). Patients without antigen shift showed a trend toward improved overall survival in comparison with patients demonstrating any degree of antigen shift. Antigen shift is seen in a significant proportion of cases of SS with long-term follow-up and may be a marker of more aggressive disease.