THE CLONAL NATURE OF CIRCULATING SEZARY CELLS

To determine if circulating Sezary cells can be classified as reactive or neoplastic based on the ability to detect the presence or absence of clonal T-cell receptor beta chain (TCR-beta) gene rearrangements by Southern blot analysis, we evaluated the peripheral blood of 25 patie nts: 11 patients with Sezary syndrome (SS), 11 with benign inflammator y dermatoses (BID), and three normal controls. Three of 11 patients wi th SS. with Sezary counts ranging from 14% to 52%, did not demonstrate any clonal TCR-beta gene rearrangements in the peripheral blood, desp ite a TCR-beta rearrangement by Southern blot analysis in the skin. Te n of 11 BID patients and all normal controls showed no evidence of a T CR-beta gene rearrangement in the peripheral blood. However, one patie nt with psoriasis demonstrated a TCR-beta gene rearrangement in the pe ripheral blood. The TCR-beta gene rearrangement detected in this patie nt, confirmed with polymerase chain reaction (PCR) amplification of th e TCR-gamma gene rearrangement, did not correlate with the presence of circulating Sezary cells or the increased risk of neoplasia. Our resu lts indicate that circulating Sezary cells may be monoclonal (neoplast ic) or polyclonal (reactive), as defined by TCR gene rearrangement stu dies. Circulating Sezary cells in SS may be reactive in nature and not accurately reflect the actual tumor burden in the peripheral blood. T he presence of circulating Sezary cells or the presence of a clone of cells defined by TCR-beta gene rearrangement in the peripheral blood i s not limited to neoplastic disease processes. (C) 1995 by The America n Society of Hematology.