Probiotic-associated high-titer anti-B in a group A platelet donor as a cause of severe hemolytic transfusion reactions.

BACKGROUND: Hemolytic transfusion reactions (HTRs) can occur with transfusion of platelets (PLTs) containing ABO-incompatible plasma. Reported cases have involved group O donors. Two cases of PLT-mediated HTRs associated with the same group A plateletpheresis component, collected from a donor taking high doses of probiotics are reported. CASE REPORT: Case 1 was a 40-year-old 69-kg group B stem cell transplant patient who received one-half of a group A plateletpheresis component. Severe back pain occurred 10 minutes into the transfusion, accompanied by anemia and hyperbilirubinemia. Case 2 was a 5-year-old 26-kg group B male with aplastic anemia who received the other half of the same plateletpheresis component, volume reduced to 37 mL. Syncope occurred immediately after the transfusion, with laboratory evidence of hemolysis a few hours later. RESULTS: Serologic investigation of posttransfusion samples from both patients revealed positive direct antiglobulin tests: C3d only for Case 1 and immunoglobulin (Ig)G and C3d for Case 2; the eluates contained anti-B. The group A donor's anti-B titer was 16,384 at saline and IgG phases. Donor lookback revealed that the donor had donated 134 apheresis PLTs over many years. For 3 years, he had intermittently taken probiotics; 3 weeks before the index donation, he began taking three tablets of probiotics every day. Lookback of prior group B recipients uncovered a case of acute hemolysis that was not recognized at the time. The solubilized probiotic inhibited anti-B in vitro. CONCLUSION: Non-group O PLT donors can have high-titer anti-A or anti-B that might mediate HTRs, and probiotic ingestion in blood donors represents a novel mechanism of stimulating high-titer anti-B.

Accelerated lymphocyte reconstitution and long-term recovery after transplantation of lentiviral-transduced rhesus CD34+ cells mobilized by G-CSF and plerixafor.

OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) in combination with plerixafor produces significant mobilization of CD34(+) cells in rhesus macaques. We sought to evaluate whether these CD34(+) cells can stably reconstitute blood cells with lentiviral gene marking. MATERIALS AND METHODS: We performed hematopoietic stem cell transplantation using G-CSF and plerixafor-mobilized rhesus CD34(+) cells transduced with a lentiviral vector, and these data were compared with those of G-CSF and stem cell factor mobilization. RESULTS: G-CSF and plerixafor mobilization resulted in CD34(+) cell yields that were twofold higher than yields with G-CSF and stem cell factor. CD123 (interleukin-3 receptor) expression was greater in G-CSF and plerixafor-mobilized CD34(+) cells when compared to G-CSF alone. Animals transplanted with G-CSF and plerixafor-mobilized cells showed engraftment of all lineages, similar to animals who received G-CSF and stem cell factor-mobilized grafts. Lymphocyte engraftment was accelerated in animals receiving the G-CSF and plerixafor-mobilized CD34(+) cells. One animal in the G-CSF and plerixafor group developed cold agglutinin-associated skin rash during the first 3 months of rapid lymphocyte recovery. One year after transplantation, all animals had 2% to 10% transgene expression in all blood cell lineages. CONCLUSIONS: G-CSF and plerixafor-mobilized CD34(+) cells accelerate lymphocyte engraftment and contain hematopoietic stem cell capable of reconstituting multilineage blood cells. These findings indicate important differences to consider in plerixafor-based hematopoietic stem cell mobilization protocols in rhesus macaques.