A NEW RADIOIMMUNOASSAY FOR THE DETECTION OF SMALL AMOUNTS OF WHITE CELLS AND PLATELETS IN RED-CELL CONCENTRATES - IMPLICATIONS FOR BLOOD-TRANSFUSION

In the procedure for quality control of red cell concentrates, made white cell (WBC)‐poor by filtration, the particle‐counting technique was found to be insufficiently sensitive in detecting the remaining WBCs and platelets. Therefore, direct radioimmunoassays were developed using murine monoclonal antibodies specific for platelets, granulocytes, and T lymphocytes. The sensitivity for platelets was 40 times 103 per mL, that for granulocytes was 10 times 103 per mL (starting from 0.2 mL of red cell filtrate), and that for T lymphocytes was 0.006 times 106 per mL (starting from 5 mL) and 0.0015 times 106 per mL (starting from 50 mL). These direct assays were used in experiments on filtration with three types of filters: the Cellselect B‐1005, B‐1014 and the B‐1013 (bedside filter). After filtration of 1 unit of blood cell suspension through the B‐1005, the number of remaining platelets was found to vary between ≤0.04 times 106 and >15 times 106 per mL (n = 16); after filtration through the B‐1013 filter, the remaining platelets were >0.04 times 106 per mL. Upon filtration of a second unit of blood cell suspension through the B‐1013 filter, the number of remaining platelets varied between ≤0.04 times 106 and 5 times 106. In both filter types, the number of remaining granulocytes was always >0.01 times 106 per mL. A study of T‐lymphocyte contamination revealed that, upon filtration of 1 unit of blood through the B‐1005, T‐lymphocyte numbers were ≤0.0015 times 106 to 0.15 times 106 per mL (starting from 5 and 50 mL); upon filtration through the B‐1013 filter, the number of remaining T lymphocytes varied between ≤0.006 times 106 and 0.2 times 106 per mL (starting from 5 mL). After filtration of a second unit of blood cell suspension through the B‐1013 filter, the number of remaining T lymphocytes ranged from ≤0.006 times 106 to 0.1 to 0.5 times 106 per mL (starting from 5 mL). The direct radioimmunoassay is an improvement over the present electronic particle‐counting techniques with regard to both sensitivity and specificity and may therefore be useful in quality control procedures in blood transfusion as well as in the development of new filters. 1990 AABB