title: Filtration of RBC units:effect of storage time and temperature on filter performance.
abstract: BACKGROUND
  The influence of time, temperature, and rate of filtration on the efficacy of WBC reduction of RBC units was studied in a controlled, paired-donor format.
  
  
  METHODS
  Ten donors underwent whole-blood phlebotomy on two to four occasions each. Units were filtered (RCXL-1, Pall Biomedical) under laboratory conditions and gravity flow as follows: 1) after 0 to 2 hours of storage at 22 degrees C, 2) after 7 to 8 hours at 22 degrees C, 3) after 14 days of storage at 4 degrees C, and 4) under mock bedside conditions after 14 days of storage at 4 degrees C. Prefiltration and postfiltration cell counts and prefiltration WBC CD11a expression were assessed on Days 0 and 14.
  
  
  RESULTS
  WBC content before filtration was 2.20 and 2.34 x 10(9) (p>0.05) for units stored for 2 and 8 hours (Groups 1 and 2) and declined to 52.8 and 7. 57 x 10(4) (p<0.01) after filtration. The efficacy of WBC reduction in units stored for 14 days was similar to that in units stored for 8 hours, but absolute postfiltration WBC counts were significantly lower because of a 0.6 log reduction in the starting WBC count after 14 days of storage (postfiltration WBC content of 1.02 and 2.31 x 10(4) for units filtered under laboratory vs. bedside conditions [p>0.05]). Filtration under bedside conditions was associated with a greater degree of variation in residual WBC counts than laboratory filtration. WBC reduction by filtration was significantly greater in units stored for at least 8 hours (Groups 2, 3, and 4) than in those stored for less than 2 hours (4.59 log vs. 3.83 log reduction in WBC content, p<0.05). Surface expression of leukocyte function antigen 1 as measured by CD11a was similar in all groups.
  
  
  CONCLUSIONS
  WBC reduction of RBC units by filtration was least effective when performed within 2 hours of collection. Efficacy of WBC reduction increased significantly after the units were stored for 8 hours to 14 days, without significant differences between these storage intervals. Laboratory filtration yielded more consistent results than did mock bedside filtration. Temperature and filtration rate had no effect on the efficacy of WBC reduction by filtration.
authors.affiliation: Department of Transfusion Medicine, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA. jsmith@dtm.cc.nih.gov
authors.forename: J D
authors.initials: JD
authors.lastname: Smith
authors.forename: S F
authors.initials: SF
authors.lastname: Leitman
mesh_terms: D001793:Blood Preservation; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology; D002470:Cell Survival; D004912:Erythrocytes; D005374:Filtration / Q000295:instrumentation; D006400:Hematocrit; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1 / Q000096:biosynthesis; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
chemical_list: D016169:Lymphocyte Function-Associated Antigen-1