Peripheral blood schistocytes in the acute phase after allogeneic or autologous stem cell transplantation assessed by digital microscopy.

INTRODUCTION: Early detection of endothelial graft-vs-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT) might help protect the patient from the late and severe complications of transplant-associated thrombotic microangiopathy (TA-TMA). Appearance of schistocytes in peripheral blood is one of the cardinal diagnostic features of TA-TMA. Our aim was to test the diagnostic accuracy and objectiveness of digital microscopy with respect to the recognition and quantification of schistocytes in the setting of endothelial GVHD. METHODS: Peripheral blood smears from 127 allogeneic and 63 autologous HSCT patients (January 2016-June 2017) were retrospectively examined before, 1 month and at 2-3 months after transplantation using digital microscopy. Peripheral blood smears from 31 healthy blood donors were also analyzed as the control group. RESULTS: Assessment by digital microscopy showed that schistocytes are significantly increased after 3 months from the allogeneic (P < .001) or the autologous HSCT (P < .001) compared to the control group. Significantly higher schistocyte counts were found in patients with acute GVHD (P = .05) and in patients with HLA mismatch (P = .005). Patients in the upper quartile of the schistocyte counts had significantly more frequently acute GVHD (P = .024) or HLA mismatch (P = .035). CONCLUSIONS: Schistocytes can be reliably counted by means of a digital microscopy system and are significantly higher in patients with acute GVHD and HLA mismatch. Inversely, patients with the highest numbers of schistocytes are more frequently affected by aGVHD, implying that high schistocyte counts after HSCT might be a surrogate marker for this complication.