Abstract:
Objective To study the expression and prognostic significance of the percentage of smudge cells or ZAP-70 in chronic lymphocytic leukemia (CLL).
Methods The percentage of smudge cells was observed on routine blood smears in a cohort of 92 CLL patients. ZAP-70 expression was determined by flow cytometry. The relationship of CLL progression with the smudge cells or ZAP-70 was analyzed.
Results Among the 92 patients, 28 (30.5%) were Binet A, 44 (47.8%) were Binet B, and 20 (21.7%) were Binet C. The percentage of smudge cells ranged from 3% to 48% (median=19%). When the cutoff value was 20 %, 56 (60.9%) of the cases were positive for smudge cells, and 32 (34.8%) were positive for ZAP-70. A high ZAP-70 expression was found to be correlated with a low percentage of smudge cells. Patients with < 20% smudge cells (according to ROC analysis) were characterized by an unfavorable clinical course, i.e., significantly shorter progress-free survival, than those with ≥ 20% smudge cells (59.4% vs. 86%, P < 0.05). Patients with positive ZAP-70 expression had a significantly shorter progress-free survival than those with negative ZAP-70 expression (57.8% vs. 79.5%, P < 0.05). Combined analysis revealed a shorter progress-free survival in patients with < 20% smudge cells and positive ZAP-70 expression (27.8%, P < 0.05) than in those with < 20% smudge cells and negative ZAP-70 expression.
Conclusion There is a close correlation between a smudge cell-negative status and positive ZAP-70 expression, which predicts unfavorable CLL prognosis.