Association of change in clinical status and change in the percentage of the CD4+CD26− lymphocyte population in patients with Sézary syndrome

Background Because there are currently many effective therapies available for Sezary syndrome, close monitoring of disease progression is required in order for a clinician to know when to institute or change an intervention. It has been our clinical experience that changes in patients' CD4 + CD26 − T-cell populations of peripheral blood lymphocytes herald changes in their clinical status. Objective Our purpose was to evaluate whether a change in patients' CD4 + CD26 − population of T cells presages a change in their clinical status. We also sought to investigate the association between a change in T-cell populations that are CD4 + CD7 − , CD8 + , CD56 + , and the CD4 + /CD8 + T-cell ratio and a change in the patient's clinical status. Methods We conducted a retrospective chart review analysis of 21 patients with Sezary syndrome who had flow cytometry, usually including levels of CD4 + CD26 − , CD4 + CD7 − , CD8 + , CD56 + , and CD4 + /CD8 + ratios measured at two time periods, 12 weeks apart. Results We report two cases in which changes in patients' clinical status were preceded by several weeks by a change in their CD4 + CD26 − level. We report weak associations between a decreasing CD4 + CD26 − T-cell population, a decreasing CD4 + CD7 − population, an increasing CD56 + population, and an improving clinical status. We also report stronger associations between both a decreasing CD8 + population and an increasing CD4 + /CD8 + ratio and a worsening clinical status. Limitations The study was limited by the number of patients and the time period over which the study was conducted. In addition, varying configurations of CD4 + CD26 − T-cell populations were observed that may have limited the utility of this measurement. Conclusions Flow cytometry assays of patients' blood and, in particular, measurement of the CD4 + CD26 − population of lymphocytes over time may be a valuable tool for monitoring patients with Sezary syndrome. There exist varying configurations of CD26 T lymphocytes that may cause differences in standards for what is considered positive and negative between observers. Further prospective analysis involving larger groups of patients is recommended.