A concerned family in a South Atlantic state asks how rare donor blood might be located for a loved one who needs transfusions, but who has an antibody against a high prevalence antigen.

This question was forwarded to Sandy Nance, Director, American Rare Donor Program and Director, National Reference Laboratory for Blood Group Serology (attribution used with permission). The American Rare Donor Program (ARDP) is a joint program with the American Red Cross and the American Association of Blood Banks and represents the partnership of the Immunohematology Reference Laboratories (IRLs) across the USA to provide rare blood products to the patients who need them. These products are usually frozen products that are thawed when needed and have a 24-hour expiration date post-thaw. In the frozen state, these products can be stored for 10 years. Sandy reports that the ARDP is best accessed through the facility transfusion service via their blood supplier.

There are several categories of rare types:

• rare for an antigen of high prevalence
• rare for common antigens in five systems
• IgA-deficient.

There are over 34,000 active donors in the ARDP database. In the December 2004 issue of Immunohematology (PDF file), there are discussions of both the ARDP program (p 239) and the International Society of Blood Transfusion (ISBT) rare donor program (p 244).

Sandy advises that if a patient's family inquires about the process for finding rare donor blood, they should be advised to ask the patient's doctor to discuss with the hospital transfusion service the need for rare donor blood. If appropriate, the hospital transfusion service should communicate this request to the blood supplier. If the blood supplier cannot supply the blood, the blood supplier calls an ARDP member (AABB Accredited IRLs and ARC IRLs). The ARDP member will review the case to ensure the completeness of the IRL work and handle it from there. This step helps ensure that, as much as possible, the blood will be compatible in that the work-up was complete and all antibodies were identified. This will help to limit the number of times blood is thawed, deglycerolized and delivered to the requesting facility and is not compatible. The ARDP helps to facilitate other phenotyped product needs (non-rare requests) by faxing the requested phenotype information to ARDP member facilities enabling the transfer of the needed phenotyped products. The database of rare donors is not used to fill those non-rare requests. This practice reserves the rare units for the patients who need rare products.

The activity of the ARDP for 2004 was projected to be 2,382 new rare donors registered, 662 requests for 1492 units. 84% of requests are completely filled with the number of units requested with an additional 2% partially filled, leaving 14% of the requests for rare blood not receiving blood products. In 2002 the number was 8%, and in 2003 it was 10%. Thus, for an increasing percent of patients, rare blood is not available. The most difficult to fill are rare blood types with an antibody to a high prevalence antigen (U. hrS, hrB, Dib, Vel, Kpb, Jsb, Yta) often in combination with other common alloantibodies. Many of these requests are for transfusion needs of patients with sickle cell anemia.

The Monocyte Monolayer Assay can be useful in predicting the clinical significance of alloantibodies; a negative result means that the antibody does not need to be honored for the current transfusion.

Another tool is the use of international inventories through the ISBT Rare Donor Program, International Donor Panel (IDP). ARDP donors are listed on the IDP and the ARDP has access to the IDP members. The IDP contains only donors negative for antigens of high prevalence and contains about 4000 donors. The ARDP is a vital link in patient care that relies on the cooperative spirit of facilities across the county combining the strengths of inventories with a powerful database.

The following comments have been received.

ADDENDA May 3, 2005

1. A medical director of a medium-sized transfusion and blood collection facility in the upper midwest suggests that for patients who are healthy enough to have their own blood collected and 'banked' for future use, the need for rare blood type RBCs can be addressed by collecting autologous blood, which can be frozen to prolong shelf life. She clearly acknowledges that while 'pre-deposit' autologous blood donation will not solve the logistical problems for patients in immediate need of rare donor blood, it can be a useful alternative to obtaining rare allogeneic donor RBC units. The major obstacle is whether or not the patient in question is healthy enough to donate, how long they can wait before they actually need a transfusion, and whether the local blood collection facility has the ability to freeze, store and deglycerolize the collected units.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator