Gamma or X-irradiation of blood components is indicated to reduce the risk of transfusion-associated GVHD.
Risk depends on:
Number of viable lymphocytes.
Susceptibility of the immune system to engraftment.
Degree of HLA-matching (higher risk when donor and recipient share a HLA haplotype).
Clinical features:
Deranged LFT (hepatitis)
Widespread skin rash
Diarrhoea
Profound marrow hypoplasia
Mortality in excess of 90%
Diagnosis: biopsy, supported by evidence of persisting donor lymphocytes (chimerism studies can be done)
Minimum dose of irradiation is 25Gy; no part of the component should receive more than 50Gy.
SHOT reporting requirements:
All cases of TA-GVHD
All near-misses: i.e. all high-risk individuals transfused with non-irradiated components.
Since universal leukodepletion, despite hundreds of near-misses, there have been no cases of TA-GVHD.
Components which require irradiation:
Red cells (except cryopreserved red cells after deglycerolization)
Irradiate within 14 days of collection.
Shelf-life: 14 days from date of irradiation.
For neonates / IUT: within 5 days of collection (shelf-life: within 24 hours of irradiation).
Platelets: irradiate at any point during storage, retain normal shelf-life after irradiation.
Granulocytes: irradiate before issue and transfuse with minimal delay.
Components which do not require irradiation:
FFP
Cryoprecipitate
Fractionated plasma products
Irradiated components not used by the intended individual can be returned to stock and given to recipients who do not require irradiated components.
All irradiated components should be labelled as such, with an approved bar code. Ideally, a radio-sensitive label should be used.
Components must be monitored with a radiation-sensitive device and the result permanently recorded.
Patients at risk of TA-GVHD should be made aware of their need for irradiated blood components, and be provided with appropriate written information and an alert-card for clinical staff.
Indications for irradiated components:
All components for intrauterine transfusion.
All components for neonatal transfusion, where the neonate has received IUT, till 6 months after the EDD (40 weeks).
All HLA-matched components.
All donations from a first- or second-degree relative.
All patients with severe T-lymphocyte immunodeficiency syndromes.
All patients with Hodgkin lymphoma (lifelong).
All patients who have received chemotherapy with a purine analogue (lifelong).
Fludarabine
Bendamustine
Cladribine
Clofarabine
Deoxycoformicin
All patients who have received alemtuzumab.
All patients who have received antithymocyte globulin (ATG).
All patients undergoing autologous stem cell transplant, from the start of conditioning chemotherapy.
Continue till 3 months post-transplant (till evidence of engraftment and lymphoid reconstitution).
If total body irradiation used (rarely now), continue till 6 months post-transplant.
All patients and healthy donors for one week prior to, and during stem cell harvest.
All allogeneic transplant patients from the start of conditioning chemotherapy. Continue as long as:
The patient is on GVHD prophylaxis (usually till 6 months post-transplant).
The lymphocyte count is <1×109/L.
If cGVHD develops, for the duration of cGVHD.
The patient remains on immunosuppressive treatment.
Conditions where irradiated products are not required:
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