Transfusion-related leukocytosis in critically ill patients

OBJECTIVE: We observed that many critically ill patients developed leukocytosis following blood transfusions. To validate this observation and to explore a possible mechanism, a prospective study was designed. DESIGN: Prospective, non-interventional study. SETTING: Surgical/medical intensive care unit in a university-affiliated community hospital. PATIENTS: Consecutive patients who required packed red blood cells transfusion. INTERVENTIONS: White blood cell count (mean +/- SD) x 10(9)/L before and 2, 4, 6, 12, and 24 hrs following transfusion of non-filtered packed red cells was measured in 96 patients. MEASUREMENTS AND MAIN RESULTS: Twenty patients were septic at the time of transfusion, whereas 76 were not. The incidence of post-transfusion leukocytosis in septic vs. nonseptic patients was 15% vs. 76%, respectively (p <.001). The white blood cell count in nonseptic patients increased from 14.3 +/- 4.8 before transfusion to 19.5 +/- 7.0 2 hrs following transfusion (p <.001) and returned to baseline in 24 hrs. In the septic group, no significant post-transfusion leukocytosis occurred. In 11 nonseptic patients requiring more than one unit of packed red cells, a significant increase in mean white blood cell count occurred 2 hrs after transfusion with non-filtered packed red cells, whereas transfusion with pre-storage-filtered packed red cells did not result in such an increase. Interleukin-8 concentrations (pg/mL) in stored non-filtered packed red cells were significantly higher after 4 wks of storage (745.5 +/- 710, p =.02) than at weeks 1 (61.2 +/- 21.6) and 2 (59.3 +/- 29). In the last 16 nonseptic patients, the units of non-filtered packed red cells were assayed for interleukin-8 immediately before transfusion. Interleukin-8 concentrations were higher in units that caused leukocytosis in the recipients compared with those that did not (408.4 +/- 202 vs. 65.1 +/- 49, p =.02). CONCLUSIONS: Transfusion of non-filtered packed red cells, but not of pre-storage-filtered packed red cells, may frequently cause an acute and transient leukocytosis in critically ill nonseptic patients. Interleukin-8 accumulating in stored non-filtered packed red cells may play a role in this phenomenon. Recognition of post packed red cell transfusion leukocytosis may avoid unnecessary investigations and therapies in false suspicion of sepsis.