Immunophenotypic Stability of Sezary Cells by Flow Cytometry.
James Vaughan, Alexandra M Harrington, Steven H Kroft, Horatiu Olteanu. Medical College of Wisconsin, Milwaukee
Background: Mycosis fungoides (MF) and Sezary syndrome (SS) are lymphomas characterized by epidermotropic neoplastic T-cells. Flow cytometry (FC) has been increasingly utilized to detect aberrant peripheral blood (PB) T-cells (Sezary cells). However, the immunophenotypic (IP) stability of MF/SS has not been well characterized. We report the IP characteristics and antigenic instability in a series of patients (pts) monitored by serial FC.
Design: Diagnostic and follow-up (f/u) PB specimens from 9 pts (2 SS, 7 MF) were analyzed by 4-color FC using antibodies against CD2, CD3, CD4, CD5, CD7, CD8, CD26, CD45RO, and CD56. A cut-off of > 20% antigen expression compared to isotype controls was used to define positive antigen (Ag) expression. A ¼ log shift in Ag intensity as compared to internal normal cell populations was used to define dim or bright Ag expression, and to define a change in expression.
Results: There were 9 pts (M:F=5:4) with a median age at diagnosis of 65 years (range 44-83) and a median f/u interval of 383 days (113-1251). A total of 109 specimens were analyzed (9 diagnostic, 100 f/u). 1-26 f/u specimens were analyzed/patient (median 13). All pts presented with an erythematous rash and Sezary cells by FC. The median absolute Sezary cell (ASC) count at presentation was 2850/µL (226-10386). A clonally rearranged T-cell receptor gene was demonstrated in 7/7 cases tested. The number of IP aberrancies (n=37) at presentation ranged from 3-5/patient (median 4), and included dim or absent CD2 (n=6), CD3 (n=6), CD4 (n=4), CD5 (n=1), CD7 (n=9), CD26 (n=9), and bright CD45RO (n=2). A change in IP was observed in 7/9 pts, and involved change in intensity, gain, or loss of Ag expression for CD2 (n=6 pts), CD3 (n=2), CD4 (n=4), CD5 (n=2), CD7 (n=4), CD26 (n=5), and CD56 (n=1). All cases retained multiple aberrancies at f/u (total=340; median 3/analysis, range 2-6). Of initial aberrancies (total=37), 90.2% were persistent at f/u. Of total aberrancies present at f/u, 51/340 (15%) were gained, including changes in CD2, CD4, CD5, CD7, CD26, and CD56. 3 pts had a large cell transformation and 13/51 gained aberrancies (27%) were detected after this event. 4 pts showed >99% decrease in the ASC count and improvement of skin lesions after treatment with alemtuzumab.
Conclusions: Minor IP changes are observed over time in the majority of pts with MF/SS; however these diseases maintain persistently aberrant IPs, and thus appear amenable to f/u with limited FC panels. ASC counts by FC correlate well with treatment response and severity of clinical symptoms, as highlighted by 4 pts who received treatment with alemtuzumab.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 231, Tuesday Morning