Blood donations are regularly tested for a number of characteristics, including ABO/Rh blood group and infectious diseases such as HIV, and Hepatitis B and C. However, platelet donations – the cell fragments in blood which help bring about the clotting response – are not routinely tested for the presence of activated platelets, a component which can have a profound effect on outcomes in the patient who receives that transfusion.
According to LightIntegra Technology, a Canadian blood diagnostics company, between 30 and 50 percent of all platelet transfusions contain activated platelets. But without a standard way to measure the proportion of activated platelets in any given bag, hematologists can’t be sure what they’re administering to patients.
So, what are the implications of activated platelets in transfusions? Surprisingly, these blood components can have both positive and negative effects depending on their medical application.
1. They Could Increase Number of Transfusions per Patient
If a patient receives two or more consecutive platelet transfusions and they are still considered to have thrombocytopenia, they are labeled as ‘refractory.’ Between 28 and 44 percent of all patients fail to adequately respond to platelet transfusions. In hematology-oncology patients, the incidence of platelet refractoriness falls somewhere between 15 and 25 percent.
While patients can experience platelet refractoriness for a number of reasons – including non-immune and immune-related causes – it is thought that the presence of activated platelets may also increase the risk of this occurrence. These patients are more likely to require additional transfusions and need a higher level of post-transfusion support compared to those who received transfusions containing only non-activated platelets.
2. They May Benefit Actively-Bleeding Patients
In cases where non-hematology-oncology patients have suffered trauma or are undergoing surgery, activated platelets may actually have a therapeutic benefit. As platelets are involved in the clotting response, patients with uncontrolled bleeding could benefit from the already-active platelet’s ability to clump and work with clotting factors at the site of injury to stop the loss of blood.
However, preventing bleeding can also increase the risk of blood clot formation in other parts of the circulatory system aside from the site of injury. Inappropriate blood clots that aren’t broken down can travel through the bloodstream and lodge in the heart, lungs or brain, potentially causing tissue damage and even death.
3. They May Interfere with Immunotherapy
Immunotherapies are increasingly being used to treat patients with certain hematological cancers, however recent studies have suggested that transfusion of activated platelets can limit this treatment’s effectiveness.
Platelet transfusions often become necessary in patients with leukemia, and other bone marrow cancers, due to the tendency of cancer cells to accumulate and impede the production of healthy platelets. Patients who have also been treated using chemotherapy and/or radiation may also require a platelet transfusion as these cancer treatments tend to deplete platelet counts.
Activated platelets have been shown to contain upregulated factors – including TGFβ, IL-6, CD40L and complement – which have an effect on the immune response. In this way, activated platelets may modulate the patient’s immune system response to immunotherapy, potentially limiting outcomes.
Screening Donations for Activated Platelets
Perhaps the best way for hospitals to determine which bag of platelets is right for which patient, mitigate potential risks, and improve patient care, is to screen platelet transfusions in the blood bank. Current methods of assessing the platelet activation status rely on visual inspection and the age of the donation. However, the immunological and inflammatory state of the donor at the time of donation are thought to affect the number of activated platelets – a variable that is not currently taken into account when classifying platelets.
By using a routine screening tool, like LightIntegra’s ThromboLUX, hospitals can significantly reduce their prophylactic platelet utilization. The tool uses Dynamic Light Scattering technology to determine the level of platelet activation in any given bag.
The test requires a small sample size of just 100µL so it is non-destructive to the rest of the platelets. It only takes a few minutes to complete, allowing blood banks to quickly determine the platelet activation status of each bag.
According to LightIntegra, hospitals using ThromboLUX have been able to reduce their prophylactic platelet utilization by about 14 percent. This is attributed to the fact that fewer patients required additional platelet transfusion support after being transfused with exclusively non-activated platelets.
Do you test your platelet donations for activated platelets? Do you think patient outcomes could be improved by transfusing hematology-oncology patients with non-activated platelets? Share your thoughts in the comments section below!