Plateletpheresis: what's new?
1995 has brought several novelties into the field of thrombocytapheresis. The most important is the presentation by Baxter of the Amicus CFC apparatus that, in a two-vein collection time of 51-53 min, collects 3.93-4.13 x 10(11) platelets contaminated by 0.2 x 10(6) white blood cells (WBC) with an efficiency of 72-74%. Similar results are obtained in 55 min, in single-needle procedures, with a collection efficiency of 70.7%, a total yield of 4.3 x 10(11) and a contamination of 0.9 x 10(6) WBC. Presently the machine cannot collect red blood cells (RBC), along with platelets, as does the DFC Haemonetics MCS3p. With this machine in mandatory single-needle procedures lasting 80-85 min, approximately 4.5 x 10(11) platelets can be collected with a WBC contamination of 3.1 x 10(6). Along with the platelet cells (PC), with the SDP PRC protocol at the end of each pass it is possible to collect aliquots of plasma red blood cells (PRBC) (10-50 mL) with a haematocrit of 65%. Depending on the number of passes and on the donor's body weight (BW), from 1 and 2 U/PRBC containing approximately 55 g of haemoglobin (Hb) each can be obtained. This method not only costs less but also immunological and viral risks for the patients are more efficiently addressed since it is possible to reduce the number of allogeneic exposures in the same transfusion event. PRBC can also be collected with the Fresenius AS104 and the Dideco Excel apparatuses. Dideco is presently using the "Genova" separation chamber, which can collect an average of 4.8 x 10(11) platelets contaminated with 0.5 x 10(6) WBC, in approximately 55 min. The ACD-A-to-blood ratio may be as low as 1/20 since the very last belts and lines are coated with non-thrombogenic substances. Therefore, there is no alteration of the quality of the platelets as evaluated with monoclonal antibodies (MoAbs) anti-CD 62, 63, 36 and 51, no extra haemorrhagic risk for the donors and citrate reactions and microaggregate formation are totally eliminated. In 1995 there has also been some rejuvenation of the older cell separators. The CS3000+ uses the TN6/PLT 30 combination of separation collection chambers. Platelets are collected in only 30 mL of plasma, and non-plasma solutions containing acetate can be used for their resuspension. The Fresenius AS204 is ready for better-quality combined platelet collection, and RBC-PC collection with Cobe Spectra is under evaluation along with the leucocyte reduction system that apparently brings leucocyte contamination down to 0.35 x 10(5). This interest in thrombocytapheresis is also the result of the challenge that thrombopoietin phase I and II trials have promoted.
Valbonesi
A M
AM
Immunohaematology Service, San Martino University Hospital, Genova, Italy.
Florio
G
G
Venturino
V
V
Bruni
R
R
D006801:Humans; D010983:Plateletpheresis / Q000639:trends*