Microparticles for diagnosis of graft-versus-host disease after allogeneic stem transplantation

Background. The differentiation between acute graft-versus-host disease (aGvHD) and infection is still a clinical challenge in patients after allogeneic hematopoietic stem-cell transplantation (HSCT). Definitive diagnosis is based on histologic findings, but a simple blood test for differentiation is missing. Methods. In a prospective study, we measured the plasma levels of erythrocyte-derived microparticles (EryMP) in 19 recipients during HSCT. Microparticles were isolated by differential centrifugation, double stained for glycophorin A (CD235) and annexin V, and analyzed by flow cytometry. Results. Eight patients developed aGvHD (42%), 15 patients developed infectious complications (79%), and two patients developed microangiopathic hemolytic anemia (11%). The levels of EryMP, as measured before conditioning therapy (535×10⁶/L in median), were not affected by total body irradiation, high-dose chemotherapy, or in vivo T-cell depletion. EryMP levels were unaffected in uncomplicated patients during aplasia (522×10 ⁶/L in median; P=0.394) or after engraftment (480×10 ⁶/L in median; P=0.594) and in patients with infectious complications or sepsis (586×10⁶/L in median; P=0.606). In contrast, in patients who developed aGvHD after HSCT, a 1.7-fold increase in the plasma levels of EryMP was observed (880×10⁶/L in median; P<0.001 compared with the time before therapy and P=0.015 compared with patients with infections or sepsis). Conclusion. Increased plasma levels of EryMP are present in patients who develop aGvHD but not in patients who develop infection or sepsis after HSCT. Therefore, EryMP are a potential, novel, blood marker that may be helpful in the diagnosis of this common complication after HSCT.