Diagnosis of Glanzmann thrombasthenia by whole blood impedance analyzer (MEA) vs. light transmission aggregometry.

BACKGROUND: Glanzmann thrombasthenia (GT) is a rare inherited platelet disorder that is characterized by spontaneous or postprocedural bleeding. The diagnosis of GT depends on identifying the dysfunction of the platelets. AIM: The aim of this study was to compare a whole blood impedance Multiplate analyzer (MEA) with the standard method, light transmission aggregometry (LTA) in diagnosis of GT. METHODS: Fifteen patients with GT were assessed on MEA and LTA using arachidonic acid (ASPI: 15 mm), (TRAP: 1 mm), collagen (100 µg/mL), ADP (0.2 mm), and ristocetin (Risto: 10 mg/mL). Whole blood samples were collected in sodium citrate and hirudin vacuum, blood collection tubes and tested within 4 h. Platelet-rich plasma was used for LTA using platelet agonists (ristocetin 1.5 mg/mL) (arachidonic acid 0.5 mg/mL) (ADP 2.5 mg/mL) and (collagen 1 mg/mL). RESULTS: The platelet count and PFA-100 results were (average and SD) 319 ± 93 × 10(9) L and 252 ± 34 s, respectively. Flow cytometry analysis showed that all samples are positive for CD42a and CD42b, whereas 9/15 samples were negative for CD61 and CD41. The other six patients had either partial or full expression of CD61/CD41. Aggregation analysis using both methods showed that all samples had no aggregation response to any of the agonists used apart from six samples which, using only the MEA, showed minimal aggregation in response to collagen (average = 14.3 ± 7 µg, which may suggest ability to detect qualitative abnormality of GPIIb/IIIa). CONCLUSION: These results suggest that the MEA is sensitive for the detection of Glanzmann thrombasthenia. Furthermore, MEA may also be able to differentiate between the subtypes of Glanzmann thrombasthenia.

Microparticle sizing by dynamic light scattering in fresh-frozen plasma.

BACKGROUND: We have previously shown that fresh-frozen plasma (FFP) contains red blood cell-derived procoagulant microparticles (MPs) that are removable by 0.2 microm filtration. Given the limitations of current methods for accurately sizing MPs, we have applied the novel approach of dynamic light scattering (DLS) to characterize the size distributions of these MPs within FFP. METHODS: Fresh-frozen plasma was prepared from blood Group A and O donations (n = 10 of each) after an overnight hold of whole blood at 4 degrees C. On the day of analysis, plasma was thawed to 37 degrees C and daughter aliquots were studied pre- and post-filtration (0.2 microm filtration device, Ceveron MFU-500, Technoclone). MP size and dispersity was assessed using a Zetasizer Nano S (Malvern Instruments Ltd), which employs a 173 degrees backscatter detector and an N5 Submicron Particle Size Analyser (Beckman Coulter) using multi-angle measurements (30.1 degrees , 62.6 degrees and 90 degrees ). The analysers presented MP size distribution graphically as intensity plots, mean size, standard deviation and polydispersity index. RESULTS: Of the instruments used, only the N5 utilizing a 30.1 degrees angle of measurement could detect MPs of the expected size distribution and demonstrate their removal by filtration. MPs (range of mean particle diameters: pre, 101-464 nm; post, 21-182 nm filtration) were significantly smaller post-filtration (P < 0.0001), but polydispersity index (median: pre, 0.746, post, 0.769) exhibited no significant change. There was no significant difference between the size of MPs from blood Group O (pre, 247 nm) and Group A (pre, 289 nm) samples (P = 0.44). CONCLUSION: Our data demonstrates that DLS offers a novel approach to assessing MP size and distribution, a technique that could be easily adopted as a means of assessing MPs within either FFP or other blood products.