Special Products

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Some patients require blood products with special qualities that may be held on site or may be required to be ordered in from NHS Blood and Transplant (NHSBT). The most common ones are listed below with a summary of the circumstances where they would be required. Please contact the laboratory to discuss requirements for individual patients who are due to be transfused.

Links to the hospital guidelines on use of irradiated and CMV negative components are under the Policies & Guidelines section of the Transfusion index.

Irradiated

Irradiated blood components are cellular blood components which have been treated to inactivate Iymphocytes (a type of white blood cell). These blood components can be irradiated by Gamma irradiation or X-ray irradiation. Irradiating blood components prevents the donor white cells replicating and mounting an immune response against a vulnerable patient causing transfusion-associated graft -versus-host disease (TA-GvHD). Irradiated products are required in the following situations:

  • Patients receiving transfusions from first or second degree relatives
  • Patients receiving a granulocyte transfusion
  • Patients receiving Human Leucocyte Antigen (HLA)-selected platelet units
  • Patients who have received the following drugs:
    • Purine analogues (e.g. Fludarabine, Cladribine, Deoxycoformicin, Clofarabine)
    • Bendamustine
    • Alemtuzumab (Anti-CD52)
    • Rabbit ATG (anti-thymocyte globulin) used for immunosuppressive therapy in aplastic anaemias. Brand names include Thymoglobuline, Genzyme
  • All intrauterine transfusions (lUT)
  • All exchange transfusions (provided that irradiation does not unduly delay transfusion)
  • Some neonates receiving red cell or platelet transfusions - only if there has been a previous IUT or if blood is from a first or second degree relative
  • Patients with Hodgkin's disease, at all stages of the disease
  • Patients receiving allogeneic haemopoietic stem cell (HSC) grafts, from the start of conditioning therapy and while the patient remains on Graft versus Host Disease (GvHD) prophylaxis
  • Allogeneic HSC donors being transfused before or during the harvest of their HSC
  • Patients with congenital immunodeficiency with defective cell mediated immunity (e.g. Severe Combined Immunodeficiency (SClD), Di George syndrome, Wiskott Aldrich syndrome, purine nucleoside deficiency, reticular dysgenesis, Adenosine Deaminase (ADA) Deficiency, Ataxia telangectasia, chronic mucosal candidiasis, MHC class 1 or 2 deficiency)
  • Patients who will have autologous HSC graft:
    1. Any transfusion within seven days of the collection of their HSC
    2. Any transfusion from the start of conditioning therapy until:
      1. Three months post-transplant
      2. Six months post-transplant if conditioning total body irradiation (TBI) has been used

CMV negative

Cytomegalovirus (CMV) is a member of the herpes group of viruses that commonly occurs in humans without incident, but can lead to serious illness in the immunocompromised and in children whose mothers contracted the virus while pregnant.

The Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) issued guidance in 2012 (available at the Department of Health website) in light of developments in transfusion practices. Because all units are routinely leucodepleted, and transfused units are given through a leucodepletion filter, there is less requirement to provide CMV-seronegative components for certain groups than previously recommended.

Currently, the following groups should receive CMV-seronegative components:

  • Intra-uterine transfusions and for neonates (i.e. up to 28 days post expected date of delivery)
  • CMV-seronegative patients receiving granulocyte transfusions
  • Pregnant women not in labour or post delivery (in an emergency, leucodepleted units may be used instead).

CMV-seronegative patients who are likely to receive haemopoietic stem cell or organ transplants currently or in the future do not require CMV-seronegative components, but should be considered for CMV PCR to allow early detection of any CMV infection (whether transfusion-transmitted or primary acquired).

For further information, see the NHSBT factsheet: CMV-negative blood components - Information for Healthcare Professionals

 

HEV negative

Hepatitis E virus (HEV) is found throughout the world in both humans and animals. HEV is not easily passed from person to person, but it can be passed on through blood transfusion and while it commonly occurs in humans without incident, it can lead to serious illness in the immunocompromised.

The Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) issued guidance in 2016 (available at the Department of Health website) that HEV negative components were required for specific patient groups.

Currently, the following groups should receive HEV-negative components:

  • Patients awaiting solid organ transplant (SOT) – from 3 months prior to date of planned elective SOT or from the date of listing.
  • Patients who have had SOT – for as long as the patient is taking immunosuppressants.
  • Patients with acute leukaemia – from diagnosis (unless/until a decision is made not to proceed with stem cell transplant).
  • Patients awaiting allogeneic stem cell transplant – from 3 months prior to the date of planned transplant and up to 6 months following transplant, or for as long as the patient is immunosuppressed.
  • Extra corporeal procedures – such as dialysis or extra-corporeal circulatory support for SOT patients or SOT patients receiving immunosuppressive medication.

As of the 1st of May 2017, all products supplied by NHSBT will have been screened as HEV-negative.

 

Apheresis/Pooled platelets

Apheresis platelet units are taken from one donor while pooled platelet units are taken from several donors and then combined to make up an adequate volume. When giving platelets to children under 16 or those likely to receive repeated transfusions, it is best practice to use apheresis units to minimise exposure to different donors.

High Titre negative (HT)

Some people produce anti-A or anti-B antibodies that are high titre (exceptionally strong reacting). Antibodies are mostly removed with the plasma when blood units are prepared, but a small number of antibodies still remain in with the blood cells. High titre antibodies may attack the patient’s own red cells even at these low concentrations. Whenever platelets or plasma products are given to a patient where donor ABO antibodies could attack recipient ABO red cells, all units should be high titre negative to prevent this. Platelets and plasma products received are routinely tested for HT by NHSBT and laboratory staff will routinely select appropriate units when ABO-compatible plasma or platelets are not available. For packed red blood cell units, the process of leucodepletion during their production is sufficient to reduce the process of ABO haemolysis, so HT testing is not necessary.

HbS negative

Haemoglobin S (HbS) is an abnormal haemoglobin that causes sickle cell disease. When patients with sickle cell anaemia (homozygous HbS) require blood, HbS negative blood should be used to prevent exacerbation of their condition. All blood given as neonatal top-ups should also be HbS negative.

Clinically Significant Antibodies

Whenever an acquired (non-ABO) antibody is detected in a patient’s blood, any crossmatches have to be manually performed to ensure that the donor red blood cells do not have the corresponding antigens that react with these antibodies. Some clinically insignificant or rare antibodies can be successfully crossmatched with virtually any unit of blood, but there are a number of clinically significant antibodies that require all units to be tested and guaranteed negative to the antigen before crossmatching can be done. The most significant ones are:

The Rh antigens D, C, c, E and e
Kell system antigens K and k
Kidd (Jka and Jkb)
Duffy (Fya and Fyb)
M (Only when reactive at 37°C)
S and s (Note this is not HbS which is an abnormal haemoglobin variant – It is an antigen group)
When patients with these antibodies require blood there is likely to be significant delay as the blood usually needs ordering from the BTS and will take several hours to be delivered.

In addition to selecting antigen-negative units for patients with the corresponding antibodies, there are occasions where antigen negative units will be selected to reduce the chance of a patient developing a new antibody. Except in extremely rare circumstances, antibodies are only produced when a person’s immune system is presented with an antigen that they themselves do not make, so the following guidelines are followed:

K negative units are given to all females of childbearing potential. Most units produced by the BTS will be Kell-typed so this should have no impact on crossmatch completion.
People likely to receive multiple transfusions are given K matched units.
People with thalassaemia are given Rh matched and K matched units.
Patients with sickle cell disease (not sickle trait) are typed for Rh, K/k, Duffy, Kidd, M, N and S. They are given Rh matched, K matched, HbS negtaive units.
 

HLA and HPA matched

Human Leucocyte Antigens (HLA) and Human Platelet-specific Alloantigens (HPA) can stimulate antibody production which will attack incompatible platelets and reduce their lifespan. By selecting HLA matched and/or HPA matched platelets for such individuals, the effectiveness of platelet transfusions can be extended.

Platelets for transfusion in infants with neonatal alloimmune thrombocytopenia (NAIT) are required to be HPA compatible. Platelets for intrauterine transfusion are required to be HPA compatible with maternal antibodies.