Quantification of red blood cell fragmentation by automated haematology analyser XE-2100.

The extent of red blood cell fragmentation in peripheral blood is useful for diagnosis and follow-up in many diseases, e.g. haemolytic uremic syndrome, transplantation-associated thrombotic microangiopathy (BMT-TMA). However, this quantification still relies on manual counting of fragmented red cells on blood smears. We have developed a quantification system by gating a fixed area of fragmented red blood cells (Gate 1) on an automated haematology analyser (XE-2100, Sysmex Co., Kobe, Japan). The fragmented red cell percentage (FRC%) calculated with this system, from 100 samples, was highly correlated with the manual count (r=0.902, P < 0.0001). Because microcytic anaemia specimens usually occupy a lower position on the XE-2100 scattergram, with microcytic cells overlapping Gate 1 and causing a spuriously high FRC% calculation, a supplementary gate (Gate 2) was added. Using the particle number in this gate as well as in Gate 1, a revised method for such samples was developed and its validity confirmed (revised FRC% correlated with a manual count for 10 subjects (P < 0.001). Because this gating system can be programmed on any XE-2100, it is likely to prove useful for accurate quantification of red blood cell fragmentation and for the monitoring of the development of BMT-TMA.

Filterability of autotransfusion blood cells and plasma after total knee arthroplasty.

Postoperatively filtered drain blood can be used for autotransfusion, but quality has been questioned. The blood contains activated or destroyed blood cells, debris, and chemicals from the wound. The ConstaVac autotransfusion system was used in 18 patients operated with a total knee prosthesis. Samples were taken from drain blood and compared with venous blood at different sampling times (to 24 h) and different incubation conditions. Micro-rheology was measured as pore filterability (5 microm) in whole blood, erythrocyte resuspension, and plasma. The filtration flow resistance was significantly lower in drain whole blood, but was unchanged in erythrocyte resuspension compared to venous blood. However, the rate of filter clogging was unchanged in drain whole blood, but was increased in the erythrocyte resuspension at 2 h. Drain plasma filterability indicated particle contamination. In total, the filterability of resuspended drain erythrocytes and cell-free plasma is affected, but this is not significant enough to have effects on drain whole blood filterability which is increased, possibly due to the leukocyte reduction. From these perspectives, we consider drain blood acceptable for autotransfusion.

In vitro evaluation of inhibitors of platelet release and aggregation.

In order to determine which drugs would be most effective as inhibitors of platelet release and aggregation, in vitro release reactions and platelet aggregometry were used to evaluate aspirin, dipyridamole, sulfinpyrazone, flurbiprofen, low molecular weight dextran (dextran 40), prostaglandin E1 (PGE1), apyrase, and adenosine. Adenosine diphosphate-induced aggregation was most effectively inhibited by PGF1, sulfinpyrazone, and dipyridamole. The latter had to be used in large doses. Collagen and epinephrine-induced release and aggregation were inhibited by the same drugs as well as by aspirin and apyrase. Antihynocyte globulin (ATG)-induced release and aggregation could only be partially blocked by these agents. In vitro studies suggest that sulfinpyrazone is one of the most effective of platelet inhibitors currently available for clinical testing.