A case of leucodepletion failure in Cobe spectra plateletpheresis: furtherstudies on the identification of the potential cause

A 54-year-old double dose donor failed leucodepletion by Cobe LRS for five sequential donations, without triggering the 'machine failure alarm'. All c ollections were uneventful but final products appeared lipaemic. The last t wo donations were studied: (i) by collecting the first half of each donatio n into one bag and the other half into a second bag. In both cases, the pro duct in bag one was leucodepleted and that in bag two 'failed' leucodepleti on. (ii) By examining the filterability of the final products using an LRF6 filter. Leucodepletion was satisfactory but showed a slightly higher level of leucocytes as compared to control or lipaemic donations, possibly due t o the presence of an interfering substance in the platelet product. (iii) B y examining the cellular content of the LRS cone and comparing it with thos e obtained from lipaemic donations from other donors. Only the test cone co ntained a large mass of waxy white material. It is postulated that this mat erial was gradually filling the cone and increasingly interfering with its leucodepleting function as the donation progressed. (iv) To monitor pre/pos t whole blood as well as the products for the presence of abnormal leucocyt e subsets. The only difference was the presence of some extra abnormal dot plot. The intensity of these extra events which was reduced both upon donat ion and filtration. We conclude that, in this case, failure of leucodepleti on was clearly donor rather than machine or process related. The implementa tion of this investigative study may help in the characterisation of the po tential cause of leucodepletion failures.