Abstract: We identified 10 trials that met the inclusion criteria with a total of 587 participants. We also identified another ongoing trial. These trials were conducted between 1975 and 2015. None of the studies included people with neutrophil dysfunction. The studies differed in the type of infections they included. Six studies included both children and adults, however data were not reported separately for children and adults. The two newest studies gave granulocyte colony stimulating factor (G-CSF) to donors; both were stopped early due to lack of recruitment. Three studies re-randomised participants and therefore quantitative analysis was unable to be performed. Overall the quality of the evidence was very low to low across different outcomes according to GRADE methodology. This was due to many of the studies being at high risk of bias, and many of the outcomes being imprecise. There may be no difference in all-cause mortality over 30 days between participants receiving therapeutic granulocyte transfusions and those that did not (six studies; 321 participants; RR 0.75, 95% CI 0.54 to 1.04; very low-quality evidence). There were no differences between the granulocyte dose subgroups (< 1 x 1010 per day versus ≥ 1 x 1010 per day) (test for subgroup differences P = 0.39). There was a difference in all-cause mortality between the studies based on the age of the study (published before 2000 versus published 2000 or later) (test for subgroup differences P = 0.03). There was no difference in all-cause mortality between participants receiving granulocyte transfusions and those that did not in the newest study (one study; 111 participants; RR 1.10, 95% CI 0.70 to 1.73, low-quality evidence). There may be a reduction in all-cause mortality in participants receiving granulocyte transfusions compared to those that did not in studies published before the year 2000 (five studies; 210 participants; RR 0.53, 95% CI 0.33 to 0.85; low-quality evidence). There may be no difference in clinical reversal of concurrent infection between participants receiving therapeutic granulocyte transfusions and those that did not (five studies; 286 participants; RR 0.98, 95% CI 0.81 to 1.19; low-quality evidence). There is insufficient evidence to determine whether there is a difference in pulmonary serious adverse events (1 study; 24 participants; RR 0.85, 95% CI 0.38 to 1.88; very low-quality evidence). None of the studies reported number of days on therapeutic antibiotics, number of adverse events requiring discontinuation of treatment, or quality of life. Six studies reported their funding sources and all were funded by governments or charities. In people who are neutropenic due to myelosuppressive chemotherapy or a haematopoietic stem cell transplant, there is insufficient evidence to determine whether granulocyte transfusions affect all-cause mortality. To be able to detect a decrease in all-cause mortality from 35% to 30% would require a study containing at least 2748 participants (80% power, 5% significance). There is low-grade evidence that therapeutic granulocyte transfusions may not increase the number of participants with clinical resolution of an infection.

Plain-language summary: The evidence is current to February 2016. In this update we identified 10 completed trials that compared giving white blood cell transfusions to treat infection compared to not giving white blood cells to treat infection. One additional trial has not yet been completed. The 10 trials containing a total of 587 participants were conducted between 1975 and 2015. The studies differed in the type of infections they included. Data from three trials were not included in the analyses because participants were included within the trial more than once. Six trials included both children and adults, but results were not reported separately for children and adults. The two newest trials gave G-CSF to donors, both were stopped early due to lack of recruitment. Six studies reported their funding sources and all were funded by governments or charities. Giving white blood cell transfusions to treat infection may not affect the risk of death or the number of people who recover from an infection. It is unknown whether white blood cell transfusions increase the risk of having a serious adverse event. None of the studies reported whether white blood cell transfusions reduced the number of days participants were on therapeutic antibiotics, or whether white blood cell transfusions had an effect on participants' quality of life. The evidence for most of the findings are of low or very low quality. This was because the total number of participants included in this review was too small to detect a difference in this review's primary outcome. We calculated that a study would need at least 2748 participants to be able to detect a decrease in the risk of death from 35 people out of 100 to 30 people out of 100 (five additional lives saved per 100 people treated). Also participants and their doctors were likely to know which study arm they had been allocated to in all of the studies.