Neutropenia is a commonly seen complication following kidney transplantation1,2 and is often managed with granulocyte colony-stimulating factor (G-CSF) which stimulates white blood cell (WBC) proliferation. Published data on solid organ graft outcomes following G-CSF treatment is limited and reports on the rates of graft rejection following treatment are contradictory2-5. The records of 310 consecutive kidney-only transplants between 2011 and 2019 were examined. From this a cohort of patients who received G-CSF for neutropenia was identified and matched 1:1 with patients from the same era who did not receive G-CSF. Variables including donor type, HLA mismatch, CMV status, induction agent and immunosuppressive regimen were matched as closely as possible. Outcome data was recorded including eGFR at 12 and 18 months post-transplantation, episodes of rejection at 12 and 18 months (biopsy-proven), graft loss at 12 and 18 months, or death. Fifty-two patients were included in the analysis, with twenty-six patients in each group (G-CSF vs. non G-CSF). Median eGFR in the G-CSF group was 42mL/min/1.73 m2 vs 51mL/min/1.73 m2 in the non G-CSF group at 12 months (p=0.25) and 42mL/min/1.73 m2 vs 48 mL/min/1.73 m2 at 18 months (p=0.33). There were 2/26 patients who had an episode of rejection in the G-CSF group vs 6/26 patients with an episode of rejection in the non G-CSF group at 12 months (p=0.24), and 2/26 patients with an episode of rejection vs 8/26 patients with an episode of rejection at 18 months (p=0.08). In the G-CSF group 1/26 patient had graft loss vs 2/26 patients in the non G-CSF group at 12 months (p=0.55), and 1/26 graft losses vs 2/26 graft losses at 18 months (p=0.55). 1 patient in each group died due to unrelated causes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT) In this small cohort of patients, treatment with G-CSF was not associated with any significant increase in rates of rejection or graft loss, with comparable graft function at 12 and 18 months. While other studies have had relatively short periods of follow up and no comparator, this study is strengthened by its long follow-up and the presence of a control group. Nonetheless, while these results are reassuring, larger prospective studies are needed in order to provide greater certainty that there is no association between G-CSF use and rates of acute rejection in kidney transplant recipients.