Leucocytosis following Transfusion with Leucodepleted Red Cells to Non-Bleeding Critically Ill Patients

Previous studies have shown that transfusion of non-leucodepleted red blood cells can cause leucocytosis in recipients. A small study suggested that pre-storage leucodepletion removed this phenomenon, but has not been further substantiated. We explored whether recipient leucocytosis occurs when leucodepleted red blood cells were transfused to non-bleeding intensive care patients. We used routinely collected data for 95 transfusions in 54 patients. Overall, no leucocytosis was found on the first routine blood sample following transfusion (mean change 0.6 × 109/L; 95% confidence interval - 0.2 to 1.3; p=0.145). However, for the 32 transfusions in patients with normal pre-transfusion leucocyte count there was a clinically small but statistically significant leucocytosis following transfusion, unlikely to have occurred by chance (mean change 1.5 × 109/L; 0.5 to 2.5; p=0.005). No significant change was observed in patients with pre-transfusion leucocytosis. We found no relation between leucocytosis and storage age of red cells. Our data suggest that transfusions with leucodepleted red cells can increase leucocyte counts in recipients. The mechanism of this effect and its clinical importance are uncertain.