| Abstract: | BACKGROUND: White cell (WBC) degradation restricts the interval between the filtration process and the assay for residual WBCs. Maintaining WBC integrity would permit extended sample storage for batching and/or shipment to centralized laboratories. The usual quality control assay for WBC-reduced red cell units requires determining the number of WBCs in the entire counting area of a Nageotte hemocytometer, which consists of 40 rows. Reducing the counting area would simplify the quality control procedure. STUDY DESIGN AND METHODS: Adsol red cell units were prepared either on the day of collection (Day 0) or on Day 1 and WBC reduced by filtration on the same day. By using prefiltration and postfiltration red cells, samples containing WBC concentrations of 15, 10, and 3 WBCs per microL were prepared by serial dilution. Identical samples were treated with glutaraldehyde and stored at either 20 to 24 degrees C or 1 to 6 degrees C. All samples were assayed on the day of component preparation and on Days 7 and 14. The numbers of WBCs corresponding to 10- and 40-row areas of the Nageotte hemocytometer were determined. RESULTS: For the conditions and WBC concentration range studied, no significant changes in WBC concentrations were observed through Day 14 for glutaraldehyde-treated samples stored at either temperature, although there were substantial decreases in untreated samples. A 10-row measurement was determined to be sufficient for identifying WBC-reduced red cell units passing the present limit of 5 × 10(6) residual WBCs. CONCLUSION: Glutaraldehyde treatment can preserve WBCs in red cell samples at least up to Day 14, which provides increased efficiency in quality control for laboratories. Current red cell WBC-reduction filters produce components that, when assayed, contain fewer than 10 WBCs per full counting area. The simplified procedure would allow reduction of the counting area by 75 percent. |
