Applications

Donor Testing

Studies have found that platelet size, microparticle (MP) and microaggregate content—collectively known as heterogeneity of the platelet-rich plasma (PRP) obtained from a donor—are associated with product viability and function of the donated platelet concentrates 1,2. Current blood collection practices do not include donor screening for PRP heterogeneity although the variability of donor PRP has been recognized. Testing for donor PRP heterogeneity might be beneficial for matching donations to recipients’ needs—homogeneous platelet concentrates are expected to benefit cancer patients to reduce transfusion failures3 while heterogeneous platelet concentrates might be beneficial for the treatment of actively bleeding patients.

What does ThromboLUX do?

ThromboLUX can characterize platelet samples based on platelet size distribution, microparticle and microaggregate content and the response of platelets to temperature stress. ThromboLUX can measure donor PRP content and predict the composition of the corresponding apheresis platelet concentrate quickly and easily without the addition of reagents or sample manipulations.

a)

a)

b) Figure 5.1 This is the ThromboLUX output. The top (A) is a homogeneous sample and in the lower distribution (B) is a heterogeneous sample with lots of microparticles and microaggregates.

b)

Figure 5.1 This is the ThromboLUX output. The top (A) is a homogeneous sample and in the lower distribution (B) is a heterogeneous sample with lots of microparticles and microaggregates.

Why use ThromboLUX?

Research involving the composition of platelet-rich plasma taken from normal volunteer blood donors has shown that:

  • The composition of platelet-rich plasma and the function of platelets is highly variable between individual donors
  • Preparation methods impact the composition and function of platelet concentrates
  • Donors can have high levels of microparticles, microaggregates and immobilized platelets
  • Platelet count is highly variable within what is considered a normal range

Therefore ThromboLUX may be beneficial for testing of donor PRP heterogeneity to provide matching donations to recipients’ needs and creating an optimal platelet product for the patient.

When can ThromboLUX be used?

During the donor screening process it is standard practice to determine the donor’s hematocrit level and have the donor complete a questionnaire prior to donation. ThromboLUX could determine the composition of the donor’s platelet rich plasma sample during the rest of the screening process.

Output

ThromboLUX performs measurements at 37°C, then 20°C, then again at 37°C; and calculates a size distribution for each temperature. ThromboLUX then uses a proprietary algorithm to analyze the size distribution at the three test temperatures. The data that is gathered during the test is used to output the following parameters: photon rate, mean particle size, gated microparticle size and intensity, gated platelet size and intensity, MP factor and the ThromboLUX Score.

The gated parameters are calculations of the size and percent intensity within two windows that represent platelets and microparticles. The window from 50nm to 550nm is used for Gated MP parameters, and the window from 550nm to infinity is used for Gated PLT parameters.

The MP Factor parameter is an estimate of the relative concentration of microparticles to platelets based on the gated parameters. If a platelet count of the sample is available, then the product of MP Factor and Platelet count gives an approximate microparticle count.

Figure 5.2 ThromboLUX Score Card

Figure 5.2 ThromboLUX Score Card

References

  1. Thompson CB, Jakubowski JA, Quinn PG et al. Platelet size as a determinant of platelet function. J Lab Clin Med. 1983 Feb;101(2):205-13.
  2. Thompson C, Jakubowski J, Quinn P et al. Platelet size and age determine platelet function independently. Blood. 1984 Jun;63(6):1372-5.
  3. Jimenez T, Patel S, Pineda A et al. Factors that influence platelet recovery after transfusion: resolving donor quality from ABO compatibility. Transfusion 2003 43 328-334