The Impact of Surface CD20 Expression and Soluble CD20 Levels on In Vivo Cell Fragility in Chronic Lymphocytic Leukemia

Background: This prospective correlation study investigated the relationship between smudge cells, surface CD20, and soluble CD20 in untreated chronic lymphocytic leukemia (CLL) patients. Materials and Methods: Blood smears were prepared manually from patient samples and stained using May-Grunwald Giemsa. B-cell phenotyping was performed at diagnosis using a FACS Canto II flow cytometer (Becton Dickinson, CA, USA). Soluble CD20/MS4A1 levels were measured using competitive ELISA. Results: A significant inverse correlation was observed between smudge cells and soluble CD20 levels (r = -0.51, p = 0.006). Similarly, surface CD20 mean fluorescence intensity (MFI) exhibited a significant inverse relationship with smudge cell percentages (r = -0.36, p = 0.04). A weak positive association was noted between soluble CD20/MS4A1 and surface CD20 MFI (Spearman’s rho = 0.34, p = 0.064). Soluble CD20 levels ≥2.2 ng/dL predicted higher smudge cell percentages with a sensitivity of 69% and specificity of 86% (area under the curve (AUC) = 0.75, 95% CI: 0.57–0.93, p = 0.021). Conclusion: This study highlights a significant inverse relationship between smudge cells and both soluble and surface CD20 in CLL patients. These findings suggest that soluble CD20 may be key to understanding smudge cell pathophysiology and could serve as a potential prognostic marker in CLL.