Quality assurance by a commercial flow cytometry method of leucodepletion of whole blood donations: initial application of universal testing and proposals for a batch-release sampling plan.
We have used the Becton-Dickinson LeucoCOUNT test to monitor residual leucocytes in whole blood by flow cytometry following leucodepletion filtration. This test was found to be quick, robust and reliable, and allowed measurement of residual leucocytes down to 2.25 x 104 leucocytes per unit, which was found to match approximately the limit of filter proficiency. The results of testing > 1000 units showed a lognormal distribution with means between log(10) 4.864 (0.73 x 105) and log(10) 5.016 (1.04 x 105) leucocytes per unit in the three different homogeneous groups of filtered units studied. The numbers of units with residual leucocytes exceeding the 5 x 106 upper threshold were 1/577, 2/457 and 0/87 in these groups. The filtration processes were validated according to the published BEST working party guidelines and were well within the 99% confidence and 95% tolerance target for the 5 x 106 upper threshold set for the UK. A sampling plan based on British Standard BS 6001 with elimination of outliers by the extreme studentized deviate (Grubbs' test) was evaluated on random samples from these groups and has been adopted locally as a prospective batch-release criterion for release of leucodepleted blood.
Barclay
G R
GR
Scottish National Blood Transfusion Service, Edinburgh and South-East Scotland Regional Transfusion Centre and Transfusion Medicine Academic Unit, Edinburgh, Scotland, UK. Robin_Barclay@compuserve.com
Walker
B
B
Gibson
J
J
McColl
K
K
Turner
M L
ML
D001782:Blood Donors; D001793:Blood Preservation; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007937:Leukapheresis / Q000379:methods*; D007962:Leukocytes; D011786:Quality Control