[1444] Immunophenotypic Stability of T-Cell Large Granular Lymphocytic Leukemia and Chronic Lymphoproliferative Disorders of NK Cells by Flow Cytometry

MD Spears, AM Harrington, SH Kroft, H Olteanu. MCW, Milwaukee, WI

Background: T-cell large granular lymphocytic leukemia (T-LGLL) and chronic lymphoproliferative disorders of NK cells (CLPD-NK) are being increasingly followed by serial flow cytometry (FC) to assess progression of disease and response to therapy. Only limited data is available on the temporal immunophenotype (IP) stability of these entities. We report the frequency of antigenic instability in a series of patients monitored with serial FC.
Design: Diagnostic and follow-up (f/u) peripheral blood or bone marrow aspirate specimens from 8 T-LGLL and 2 CLPD-NK were analyzed by 4-color FC with antibodies against CD2, CD3, CD4, CD5, CD7, CD8, CD16, CD56, and CD57. Normal cell populations served as internal controls for assessing antigen expression. Abnormal antigen expression was defined as a shift of at least 1/4 log in fluorescence intensity. Clonality was assessed by molecular testing, Vbeta and/or KIR usage analysis in all cases.
Results: There were 10 patients (M:F=5:5) with a median age of 53.5 years (range 47-72), and a median f/u of 8.8 months (range 0.6-39.7). 2-16 specimens were analyzed/patient (total=48 analyses). At presentation, 7/10 cases had cytopenias. All T-LGLLs showed aberrant (dim or bright) expression of at least 2 T-cell markers, including CD3, CD5, CD7, and CD8, in addition to expressing CD16+ in 3/7, CD56+ in 2/7, and CD57+ in 7/8 cases. CLPD-NK were CD2+ in 2/2, CD7 dim+ in 2/2, CD8+ in 0/2, CD16+ in 1/2, CD56+ in 2/2, and CD57+ in 2/2 cases. 39 total aberrancies were present at diagnosis (median 4/case; range 2-6). The mean absolute count of abnormal cells at diagnosis was 0.75 x 103/μL (0.6-1.95). Clonality was demonstrated in 5/5 cases by PCR, in 3/3 by Vbeta, and in 5/5 by KIR analysis. A change in IP was observed in 3/10 T-LGLL patients: CD3 (1 case: + to bright+), CD7 (1 case: + to dim+), CD8 (2 cases: + to bright+), CD56 (1 case: - to partial dim+), and CD57 (1 case: + to bright+, partial+ or -). All cases retained multiple aberrancies at f/u (total=136; median 3/case; range 2-6). Of the initial aberrancies, 119/136 (87.5%) were persistent, 6/136 (4.4%) were lost, and 11/136 (8.1%) were gained at f/u. 3/4 patients that required chemotherapy demonstrated IP shifts (p=0.03).
Conclusions: Although minor IP change are observed over time in approximately 1/3 of patients with T-LGLL/CLPD-NK, these disorders overall maintain stable, aberrant IP, and thus appear amenable to f/u with limited FC panels. Interestingly, our data also suggest a possible association between chemotherapy and IP changes.
Category: Hematopathology

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 201, Tuesday Morning


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