FAQs

Apheresis Platelets vs. Whole Blood-derived Platelets?

This is a very interesting question, and one that, quite frankly, my opinion has changed a little bit on in the last few years.

Traditionally, platelets collected by apheresis (sometimes called "single donor platelets," and more properly designated as "apheresis-derived platelets" or "AD-PLTs") have been considered a better option in many cases than whole blood-derived platelets (abbreviated "WBD-PLTs" and often called "random platelets"). Here are some of the typical answers you might have heard from a Blood Banker if you had asked for the benefits for AD-PLTs ten to fifteen years ago:

  • Reduced exposure to potentially infectious donors
  • Reduced HLA immunization (due to fewer donor exposures)
  • Fewer febrile nonhemolytic reactions
  • Better response in "refractory" patients (those who don't respond well to platelet transfusion)

Over the last few years, though, some of the items on this list have gradually either been disproven or have fallen into question. As we have learned more about leukocyte reduction and its effects, for example, we have realized that HLA immunization is really better prevented through removing white cells from a bag of platelets, and it really doesn't matter whether the unit is from one donor or from multiple donors, provided it is leukocyte reduced (This was very elegantly proven, by the way, in the so-called "TRAP" study published in the New England Journal of Medicine in 1997).

Febrile reactions, likewise, are better prevented with leukocyte reduction, in particular leukocyte reduction that occurs before the unit enters storage (more on that is in the section on prevention of febrile reactions). Finally, someone who is refractory to platelet transfusion may indeed be treated with AD-PLTs, but usually only after demonstration of the presence of either HLA-specific or platelet-specific antibodies. With those antibodies, the product of choice would be either HLA-matched or platelet-crossmatch compatible AD-PLTs. For those patients who are refractory for non-immune reasons (fever, splenomegaly, antibiotics, etc.), I see no advantage for apheresis over random platelets.

OK, so that leaves us with the first item on the list: Reducing exposures to potentially infectious donors. For my money (which is sadly a very small amount), this is really a pretty decent reason to choose AD-PLTs! Most people think that one donor exposure per platelet transfusion for AD-PLTs as opposed to five or six exposures in most cases from WBD-PLTs is a good idea. In addition, recent studies have suggested that apheresis platelets are less likely to be contaminated with bacteria than pooled platelet concentrate. So, we are talking about a strategy that could reduce the risk of transfusion-transmitted viral infections as well as bacterial contamination. The blood banking industry has promoted this strategy for years, to the point that roughly 85% of platelets transfused in the United States today are AD-PLTs.

However, I should also tell you that there is a growing movement in the transfusion medicine community back in the direction of the use of WBD-PLTs, especially in trauma and other immediate-need settings where repeated transfusion is not anticipated. Current non-bacterial infectious disease testing is so efficient and excellent that the risk of transfusion-transmitted viruses is really small, even if multiple donor exposures are occurring. Also, improvements to bacterial detection in platelets, such as the approval of a pre-issue bacterial detection method for pooled platelets (Verax Platelet PGD test), have lessened the risk of bacterial sepsis resulting from WBD-PLT transfusion. Finally, blood centers everywhere are understanding that the judicious use of WBD-PLTs can really ease the burden of significant supply and demand discrepancies that happen all the time with AD-PLTs, as WBD-PLTs are potentially a vast, unused resource (since we don't make platelets from the vast majority of whole blood collections currently). As a result of all these factors, the use of WBD-PLTs is growing in settings such as trauma and massive transfusion (though not yet in chronically transfused patients such as those with hematologic malignancies and progenitor cell transplants). I agree with this philosophy.