Monoclonal B-cell lymphocytosis (MBL), a precursor of chronic lymphocytic leukemia (CLL), can be present in healthy blood donors. This raises the concern that MBL transmission from blood transfusions may cause CLL in blood transfusion recipients.
Researchers recently examined the long-term health of 1.5 million donors and 2.1 million transfusion recipients using a database from Danish and Swedish blood banks. Although MBL status of donors was not known, researchers were able to determine those who later developed CLL. The researchers then compared the incidence of CLL among 7,413 transfusion recipients from 796 donors who developed CLL after donation, and over 80,000 recipients of blood from matched donors who remained CLL-free. The study did not find an association between transfusion-transmitted MBL and development of CLL (relative risk = 0.94, 95% confidence interval 0.52-1.71). Thus, the transfusion of MBL-contaminated blood should not be considered a risk factor for CLL.
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