Analysis of Blood Group Antigens as Risk Factors for Thrombosis in Polycythemia Vera Patients

Polycythemia vera (PV) is characterized by the abnormal proliferation of red blood cells (RBCs). Thrombosis and associated cardiovascular diseases are leading causes of mortality in patients with PV. This study aimed to investigate the association of Lutheran/BCAM (CD239) and other RBC antigens with thrombosis in PV.

This single-center, prospective study consecutively enrolled 50 PV patients, 39 with secondary polycythemia, and 20 healthy controls (HC) who visited the apheresis unit for phlebotomy between May 2022 and September 2023. The normalized expression levels of Lutheran/BCAM (CD239), Indian (CD44), LW/ ICAM (CD242), and Rh-related integrin-associated protein (IAP, CD47) antigens were assessed by flow cytometry. JAK2V617F expression was quantified and coagulation parameters were analyzed. Laboratory and clinical data were retrieved from the medical records.

PV patients exhibited significantly higher mean fluorescence intensity (MFI) for Lutheran/BCAM: 45.2 ± 32.8 vs. 33.0 ± 14.4, p = 0.047, Indian (CD44): 13.5 ± 18.4 vs. 8.6 ± 1.1, p = 0.195, and IAP (CD47): 604.8 ± 193.2 vs. 514.9 ± 63.2, p = 0.036 compared to HC. The Indian (CD44) antigen was identified as a risk factor for thrombosis with an odds ratio (OR) of 1.359 (95% confidence interval [CI]: 1.003 - 1.842) in a multivariable model. Positive JAK2 measurable residual disease (JAK2-MRD) (expression was detected in 100% (25/25) of PV patients assessed, with a median variant allele frequency of 51.8% (95% CI: 45.4 - 65.0%).

Higher expression of Indian (CD44) MFI levels in RBCs were associated with thrombotic events in patients with PV. Assessing RBC Indian (CD44) expression may serve as a potential biomarker for thrombotic risk stratification and prevention in PV.