Hemolysis during leukocyte-reduction filtration of stored red blood cells

Hemolysis has been reported in red blood cells (RBCs) that have undergone l eukocyte-reduction filtration. This study investigated whether the age of R BCs or the filter type affected hemolysis. One hundred eighty units of RBCs (adenine-saline added) were leukocyte-reduced by filtration. At each of th e 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" filt er. Filtration was performed with strict adherence to the manufacturers' di rections. Pre- and post-filtration samples were assayed for plasma hemoglob in by measuring the plasma absorbances at 578 nm and 562 nm. The increase o f plasma hemoglobin concentration following filtration was significantly gr eater (p < 0.05) in older units, compared to fresher units, when the Sepace ll and BPF4 filters were used. For example, the increase of plasma hemoglob in at week 6 (83.47 mg/dl:Sepacell, 128.93 mg/dl BPF4) was significantly gr eater 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 incre ase of plasma hemoglobin concentration post-filtration was significantly gr eater 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 increa sed 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.