A Report of Fourcases of Severethrombocytopenia with Rh G-CSF Mobilized Allogeneic Peripheral Blood Stem Cell Transplant Donors

Background and Objective: Granulocyte colony-stimulating factor (G-CSF) is used to mobilize progenitor cells into the peripheral bloodin healthy donors. Thrombocytopenia is one of common side effects of G-CSFmobilization, but seriousthrombocytopenia is rare. Herein,we report serious thrombocytopeniain 4 allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) healthy donors induced by recombinant human G-CSF (rhG-CSF) mobilization.

Methods: The donor received 10ug/kg/d G-CSF via subcutaneous injection.The blood parameterswere examined every day, Abdominal ultrasound detected the spleen size before, during, and after rhG-CSF mobilization.

Results: From April 2015 to May 2020, 1127 donors received hematopoietic stem cell mobilization, the percentage of serious thrombocytopenia in healthy donors was 0.35%.The count of white blood cell increased to the 4-7 timesbasic level of (35.4x109/L)after rhG-CSF mobilization 4 days, the lowestcount ofplatelet was 22x109/Lafter single postharvest. After mobilization, length of spleen increased 0.6-1.3 cm (median 10.1 cm), thickness ofspleenincreased 0-1.3 cm (median 3.4 cm). There were no obvious bleeding symptomsafter mobilization in four cases of donor.The quality of stem cell collection was relatively poor in 3 of the 4 donors, the number of mononuclear cells (MNC) was 7.47-18.58×108/kg, and the value of CD34+ was 0.82-2.42×106/kg (CD34+ proportion: 0.11-0.16%). The quality of stem cell collection in the other 1 donor was satisfactory, the number of MNC was 9.29-11.75×108/kg, and the proportion of CD34+ was 0.26~0.38%. Platelet count of 4 donors recovered to the basal level 3-10 days after drug withdrawal.

Conclusion:The severe thrombocytopenia caused by rhG-CSF mobilization healthy donor is very rare.while, the mechanismis unknown. Some studies suggested that it may be related to the insufficient expression of megakaryocytes proliferation-related genes, such as PF4 and PTFN4. Other studies indicated that rhG-CSF may aggravate the immune-mediated thrombocytopenia, which leads to hypersplenism and extensive activation of reticuloendothelial cells, thus increasing the consumption of platelets.In addition, the probability of severe thrombocytopenia was increased in allergic donors after rhG-CSF mobilization.In our report, although there was thrombocytopenia, mobilization was not affected.After the mobilization of rhG-CSF, platelets changes should be closely monitored to keep alert of donor bleeding tendency. While ensuring safe collection of hematopoietic stem cells by donors, patients should not be placed in extreme danger of not being able to receive allogeneic hematopoietic stem cells on time.

Key words:Severe thrombocytopenia;Healthy donor; rhG-CSF; Mobilization; Allogeneic peripheral blood stem cell transplantation.