Issues arising from the discovery of unexpected antibodies in plateletpheresis products

A transfusion medicine physician who works at a hospital that collects the majority of their platelets by automated technology wonders what other institutions do with blood products that contain unexpected red cell alloantibodies with respect to:

• Donor management (accept/defer for future donations; counseling the donor about the antibody)
• Product management (destroy or distribute the collected unit)
• Transfusion strategies (procedures/policies for transfusion of blood products that contain unexpected red cell antibodies

The inquiring colleague reports that his institution currently destroys any blood product that contains an unexpected antibody, and that the donors of these units are not generally informed. In the past, before his hospital began to collect platelets by automated technology, they would need to discard an occasional whole blood donation. However, now that they are collecting a large number of pheresis platelets, they wish to reconsider their local policy of destroying products that contain unexpected antibodies.

In reconsidering their local policy, the inquiring physician comments that they often transfuse incompatible ABO antibodies (group O donor platelets into group A or B recipients), so the relative risks of transfusing anti-D, C, or K should not be prohibitive. What do other institutions do regarding the above issues of donor management, product management, and transfusion strategy?

The following comments have been received.

ADDENDA Apr. 7, 2004

1. A colleague in New York reports that at his hospital they resort to washing of red cells and platelets when a donor unit contains a known red cell alloantibody. They also avoid transfusing such a product in question to someone positive for the red cell antigens involved. He adds that (in his opinion) justifying the infusion of anti-D, anti-C, anti-K and other unexpected antibodies based on the level of "safety" of infusing anti-A and anti-B in platelet concentrates into non-group O recipients is open to debate. In addition, the actual risk of infusing incompatible ABO antibodies is not fully appreciated by many colleagues in practice. He points out that in his experience the giving of non-plasma depleted O platelets to non-O's is clearly not optimal in many cases and leads to massive hemolysis in rare instances. Consequently, he would not justify infusing anti-Jka or anti-C into antigen positive recipients merely because it is unfortunately necessary to employ (in his opinion) a more dangerous practice (infusing ABO antibodies into some recipients) when managing platelet inventories.

ADDENDA Apr. 8, 2004

2. A colleague from the Pacific Northwest states that they have a very active and healthy plateletpheresis program at her facility, and have established the following policies:
   • Plateletpheresis donors are carefully chosen and pre-screened prior to being accepted into the program. Among other criteria, they must not have had prior whole blood donations with unexpected alloantibodies. If any donor tests positive for antibodies on two occasions, they are notified of the results and requested not to donate for the community.
   • Collected units positive for alloantibodies are destroyed.
   The experience with their consignees has been that they will not transfuse red cells (or other products) with alloantibodies. She states, "This has shaped our policy to notify, defer, and discard these products."
   
   
3. A quality manager from a hospital-based donor center in Southern California states that they continue to accept whole blood donations from donors with known antibodies. They do label their donation record that they are not acceptable for plateletpheresis and that FFP should not be prepared from their whole blood collections. They label the unit with the identified antibody and, if the antibody reaction strength is greater than 2+, they label the unit to be issued as saline washed cells only. She concludes, "As a smaller hospital based program, we feel we can handle the deviation from normal that this situation causes; however, if we were a larger donor facility distributing units to other hospitals, our decision may differ."
   
   
4. Stephen Apfelroth, M.D., Ph.D., Director of the Blood Bank at Jacobi Medical Center, Albert Einstein College of Medicine, Bronx, NY (attribution used with permission) states: "The comparison to ABO antibodies in ABO-incompatible platelets is not entirely valid, as anti-A and or anti-B may be adsorbed by circulating A or B substance in the recipient plasma. Not infrequently we have had to give A plasma to group AB patients, and have not observed any adverse effect. However, this may not be so for high-titer anti-A,B, and is certainly not so for anti-D or anti-Kell."
   
   
5. A quality manager from a blood bank in Cantabria, Spain believes that the problem with blood components that contain large amounts of plasma (i.e. FFP, plateletphereses, and platelet concentrates from whole blood) with irregular antibodies (IA) is that they may be transfused to an inappropriate recipient. Fortunately, the number of donors with IA is low, so they don't realize a great loss of products or donors.
   
   The Spanish colleague offers their facility's policies:
   • We consider donors with IA unsuitable for apheresis, defer them from apheresis for a year, while they are counseled to donate whole blood. After this period they are accepted for apheresis again if the IA is not detected, or to go on donating whole blood if IA is still present.
   • We discard apheresis products containing IA, and use them for quality control. This is a different problem from ABO incompatible platelets. These we use in case that compatible ones are not available, if there is urgent need.
   • We discard FFP and platelet concentrates derived from whole blood  containing irregular antibodies. The amount of plasma contained in the red cell concentrate is very low (we produce buffy coat depleted cells, in which centrifugation steps are intense), so we distribute them without washing. This practice has been in place at least for ten years, without reports of untoward events.
   • Usually, new donors are told to donate whole blood once prior to being accepted for apheresis donation. Therefore we are able to detect most IAs and avoid this problem, and at the same time produce a red cell product.
     
     
6. A physician from a blood center in Barcelona, Spain states that they do not accept blood donors with unexpected antibodies for plateletpheresis or plasmapheresis donation. In the near future, they are planning to make a plateletpheresis product with additive solution. This could be an approach to this problem as the amount of plasma in this plateletpheresis will be very low. He also states that in fact their center is currently producing pooled platelets from buffy coats with additive solution. The transfusion services often transfuse these ABO-incompatible pools to patients (e.g. group O pool to group A patient) without washing the pool.
   
   
7. The blood bank supervisor from a prestigious Boston hospital reports that at their facility they "wash" pheresis platelets that contain unexpected antibodies. The washing procedure involves removing the plasma and resuspending the platelets in normosol. After washing they will transfuse the product to any patient.
   
   She adds that they perform an isohemagglutinin screen on all group O pheresis donors and products received from other facilities. They test each of their donors only once. Their screen will detect anti-A and anti-B at a titer of 200 at immediate spin. If the donor or product tests positive they will use the product only for group O patients. If washed, a product that tests positive can be given to any patient except non-group O infants. If the donor tests negative, they will transfuse the product to any patient but will try to give it to a group O patient.
   
   
8. A colleague in Sacramento, California reports that his blood collection center currently defers donors (except in unusual circumstances) who have clinically significant (e.g., 37 degree / AHG-reactive) alloantibodies. These donors are notified via letter of the reason for their deferral. Likewise, they discard, or use for research purposes, blood components directly associated with the antibody-positive test. They do not retroactively discard any components that might have previously tested as antibody negative. The responding colleague comments that his center has previously discussed the above policy with client hospitals (> 8 years ago) in an attempt to update the policy to allow antibody-containing units to be used for selected patients, such as patients whose plasma already contains the exact same antibody specificity and who must receive RBC units that lack the corresponding alloantigen; however, the hospitals were not interested at that time. They used to wash RBCs from such donors, but ultimately decided that it was cost-ineffective, particularly given their strong donor base. The responding colleague thinks that one day he will make a concerted push to encourage client hospitals to use such units in selected circumstances. As a related aside, his donor center does collect allogeneic blood from donors who have very high frequency alloantibodies, such as anti-Yta. However, such RBCs almost always are used for patients (including autologous use) who lack the corresponding high frequency antigen. Plus, such rare RBCs usually are frozen-thawed, thereby removing virtually all of the antibody.

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