Hemolysis during leukocyte-reduction filtration of stored red blood cells

Hemolysis has been reported in red blood cells (RBCs) that have undergone leukocyte-reduction filtration. This study investigated whether the age of RBCs or the filter type affected hemolysis. One hundred eighty units of RBCs (adenine-saline added) were leukocyte-reduced by filtration. At each of the 6 weeks of shelf life, 10 units were filtered with the "BPF4" filter, 10 units with the "Purecell RCQ" filter, and 10 units with the "Sepacell" filter. Filtration was performed with strict adherence to the manufacturers' directions. Pre- and post-filtration samples were assayed for plasma hemoglobin by measuring the plasma absorbances at 578 nm and 562 nm. The increase of plasma hemoglobin concentration following filtration was significantly greater (p < 0.05) in older units, compared to fresher units, when the Sepacell and BPF4 filters were used. For example, the increase of plasma hemoglobin at week 6 (83.47 mg/dl:Sepacell, 128.93 mg/dl BPF4) was significantly greater than at week 1 (7.07 mg/dl Sepacell, 4.77 mg/dl BPF4) (Sepacell: p = 0.008; BPF4: p = 0.006). For units stored 1, 2, 4, 5, or 6 weeks, the increase of plasma hemoglobin concentration post-filtration was significantly greater with the BPF4 filter, compared to the Purecell RCQ filter (p < 0.045); for units stored 5 weeks, the increase in plasma hemoglobin concentration post-filtration was significantly greater with the BPF4 filter compared to the Sepacell filter (p = 0.009). Mean filtration times were significantly longer in older units compared to fresh units. This study shows that increased storage duration of RBCs (adenine-saline added) is attended by greater hemolysis during leukocyte-reduction filtration and by prolongation of the filtration time. In addition, the amount of hemolysis may be influenced by the type of filter.