Monitoring Red Blood Cell Chimerism with Flow Cytometry

Monitoring the change of cell populations within patients after hematopoietic stem cell transplant (HSCT) is crucial for determining the success of treatment. With current studies largely focused on determining mixed chimerism of nucleated cells, mixed chimerism for non-nucleated red blood cell (RBC) populations was rarely studied. In this study, based on the differences between donor and recipient ABO blood group surface markers and using commercially available mouse monoclonal antibodies (mAbs) for anti-A1 and anti-glycophorin A (GlyA), a flow cytometry (FCM) based assay was tested to monitor RBC chimerism for post-HSCT patients with combinations A1/O, A1B/O, A1/B, and A1B/B blood group difference. Titration curves of mixed blood type combinations with 10% margins were made. These titration curves had a consistent R2 value > 0.99 and a standard deviation (SD) value < 5%. This suggests that the proposed assay was valid, precise, and reliable. Furthermore, a patient sample with recipient A and donor O mixed blood type was tested and showed that the proposed assay was accurate. Since anti-A2 and anti-B mAbs were not tested, next steps would be testing these antibodies such that the assay can monitor post-HSCT patients with combinations A2/O, A2B/O, A2/B, A2B/B, AB/B, and B/O blood type difference.