Selecting donor red cell units for a patient with anti-Js^a that is no longer detectable by routine antibody screening

A colleague reports that they are treating a patient who has been shown to have anti-Js^a, but the antibody is no longer detectable by standard antibody detection testing. In addition, commercial Js^a typing sera are not available through any manufacturer to type donor units, to assure they are Js^a negative. Given the aforementioned situation, how would others assure that the patient is not being transfused with Js^a positive units? The inquiring colleague has a sickle-cell disease patient with this exact problem and they face this practical question frequently whenever the patient must be transfused.

The following comments were submitted in response.

ADDENDA July 26, 2010

1. A transfusion medicine physician in Ohio comments that as a general rule (as many seasoned blood bankers know) just because an antibody is no longer detectable does not mean it is no longer clinically significant. In the case of anti-Js^a, this is an antibody which may not cause a clinical transfusion reaction, but if it does the reaction can be moderate and delayed in character, according to Reid and Lomas-Franicis in the Blood Group Antigen Facts Book. Furthermore, according to Geoff Daniels in his book, Human Blood Groups, there have been two case reports of delayed hemolytic transfusion reactions in patients in which anti-Js^a was barely detectable. Based on the aforementioned, the Ohio physician would 'honor' the prior history of anti-Js^a, if possible. However, sometimes practical considerations, such as the absence of anti-Js^a typing sera, make this virtually impossible.

ADDENDA July 27, 2010

2. Another transfusion medicine physician in Ohio writes that the antigen, Js^a (KEL6 ) is a low frequency antigen in the Caucasian population (~0.01%), and that the majority of blood donations in the US are made by Caucasian individuals. Therefore, the "odds" favor most donated RBC units being negative for Js^a. However, the responding Ohio physician wonders points out that if the patient in question has any other antibodies or if the inquiring institution is selecting partially phenotyped RBCs for sickle cell disease (SSD) patients, the RBC units selected might be from donors of African American descent where the Js^a antigen is found in greater incidence (~20%). Such a scenario would increase the risk of a Js^a positive RBC unit being selected for transfusion.
   
   Regardless if the donors used for this patient are Caucasian or African American, there should be close communication with the clinical service regarding transfusion therapy in this patient. While acute situations may of course arise, in the Ohio physician's clinical setting the SSD patients come in for *scheduled* red cell transfusion and the SSD patient coordinator communicates with their transfusion coordinator so the blood bank can order in advance units which is helpful in cases like this. There should also be close communication with the blood supplier, which might have either historically typed donors (Js^a negative) which might be an option and/or may have DNA/molecular testing available for the unit. While the questioner's transfusion service would not be able to confirm the antigen negative status serologically a deviation from SOP could be considered with medical director approval. The transfusion service could consider doing DNA testing for Js^a antigen on their units (they would be definitely in the minority of labs if they elected to do this as the CAP J survey supplemental questions have shown).
   
   
3. A Supervisor at a hospital laboratory in New Jersey reports that they try to freeze patient's serum from the time when anti-Js^a is reacting, and then thaw aliquots of the reactive sample to use for verifying that a donor RBC unit lacks Js^a. They also use this strategy for other antibodies when they are not available as commercial anti-sera.
   
   
4. A transfusion medicine physician at an academic medical center in California suggests that if phenotyping a donor unit for the Js^a antigen is not possible, the transfusion service may consider ensuring that the RBC unit given is collected from a Caucasian donor, since the Js^a antigen is a low incidence antigen among Caucasians (0.01%). On the other hand, African American donors should be avoided as 20% are expected to be Js^a positive.

ADDENDA Sept. 1, 2010

5. The colleague who initiated this discussion is very grateful to those colleagues who provided feedback. Based on the feedback, her hospital decided to ask their blood product supplier for Molecular/DNA tested units to have Js(a) antigen negative units on hand. Unfortunately, the response from their supplier was "They don't do that any more". The supplier was then asked if they could disclose which RBC units on hand were collected from Caucasians, to reduce the risk of delayed transfusion reaction due to anti-Js(a). The supplier claimed that it was against HIPPA rules to give the race of the donor. The colleague who needs to treat the patient is dismayed. She can understand the need to not give out the race of every blood donor, but she cannot understand why in a case where there is a legitimate "need to know", they cannot know. She asks (rhetorically) "Aren't there any exceptions to these rules"?

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