Easy discrimination of hematogones from lymphoblasts in B-cell progenitor acute lymphoblastic leukemia patients using CD81/CD58 expression ratio.

INTRODUCTION

The discrimination of leukemia lymphoblasts (LB) in diagnosis and follow-up of B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) by multiparameter flow cytometry (MFC) may be difficult due to the presence of hematogones (HG). The aim of this study was to compare lymphoblasts of BCP-ALL and HG for the expression of the most discriminating antigens.

METHODS

A total of 82 bone marrow samples (39 BCP-ALL and 43 patients with HG) were analyzed using MFC. Mean fluorescence intensity (MFI) was measured for ten markers commonly used in hematology laboratories: CD45, CD19, CD10, CD34, CD38, CD20, CD22, CD58, CD81, and CD123. Statistical comparison of the MFI between LB and HG was performed. The presence on LB of aberrant expression of myeloid and/or T-cell markers was also investigated.

RESULTS

Qualitative pattern expression of antigens showed overexpression on LB of CD58, CD22, CD34, CD10 and underexpression of CD81, CD45, CD38 when compared to HG. Expression of CD123 was positive in 34% of BCP-ALL LB and always absent on HG. Aberrant antigen expression (myeloid and/or T-cell marker) including CD123 was observed in 58% of BCP-ALL patients. The use of a MFI antigen ratio of the most discriminating markers (CD81/CD58) (analysis of variance, P < 0.005) increased the distinction of LB versus HG with a high specificity and sensitivity as demonstrated by the use of ROC curve analysis (AUC of CD81/CD58: 0.995).

CONCLUSION

We demonstrate in this study that routine use of the MFI antigen ratio (CD81/CD58) in addition to the MFC evaluation using WHO classical criteria appears to be an efficient approach to discriminate LB from HG.