Irradiation Of Blood Components

TA-GVHD is a rare, potentially lethal disorder caused by the engraftment and proliferation of donor lymphocytes in the transfusion recipient.3667 Viable donor lymphocytes in the transfused blood component recognize the HLA antigens of the recipient and mount an immune response. TA-GVHD was first reported almost four decades ago and, to date, over 200 cases of TA-GVHD have been reported. The true incidence is unknown, as it is thought that many patients with TA-GVHD go unrecognized and additional cases are underreported, but it is estimated that TA-GVHD occurs in 0.1-1.0% of patients with hematologic malignancies.6768 While TA-GVHD occurs more commonly in immunocomprised patients, numerous cases have occurred in immunocompetent patients.

TA-GVHD can be prevented by gamma irradiation of blood components prior to transfusion. The standard dose of irradiation is 2500 cGy (25 Gy or 2500 rad) targeted to the central portion of the container, and a minimum of 1500 cGy targeted to all other areas of the component. The maximum dose should not exceed 5000 cGy.67 68 The only indication for the irradiation of blood is to prevent TA-GVHD. Those at risk for TA-GVHD are still being defined, but most authorities would agree that the patient groups listed in Table 104.3 should receive irradiated blood components.67-70 Some hospitals have opted to simply irradiate their entire blood supply in order to avoid this complication of transfusion.

All cellular blood products have been implicated in causing TA-GVHD. The clinical presentation of TA-GVHD generally includes fever, rash, diarrhea, and evidence of liver dysfunction.67 68 Fever is often the presenting sign and may occur as early as 4 days

Table 104.3 Patients at risk for TA-GVHD who should receive irradiated blood products67-70

Significant risk

Patients undergoing hematopoietic stem cell transplantation (allogeneic or autologous) Recipients of a stem cell transplant (allogeneic or autologous)

Congenital immunodeficiency syndromes

Intrauterine transfusions

Exchange transfusions in neonates

Patients receiving HLA-matched platelet transfusions or donors known to be haplotype-homozygous

Patients with Hodgkin's lymphoma

Transfusions from biologic (blood) relatives

Chronic lymphocytic leukemia treated with highly immunosuppressive purine analogues (e.g., fludarabine)

Possible/probable risk Other hematologic malignancies (e.g., acute leukemia, non-Hodgkin's lymphoma)

Immunosuppressed patients with solid tumors receiving immunosuppressive and myeloblative thrapy (e.g., neuroblastoma, rhabdomyosarcoma, glioblastoma, immunoblastic sarcoma)

Immunosuppressed solid organ transplant recipients Premature neonates

Recipient-donor pairs from genetically homogeneous populations (e.g., Japan)

No defined risk Patients with acquired immunodeficiency syndrome (AIDS) Full-term, healthy neonates

Patients receiving immunosuppressive medications posttransfusion. Pancytopenia (particularly leukope-nia and thrombocytopenia) develops late in the course (median 16 days).67 68 Infection or hemorrhage are the most common causes of death, occurring within 3 weeks of onset.67 68 Treatment is rarely effective, and the mortality rate is >90%.67 68 In our institution, as in many others, patients with hematologic malignancies, as well as those who have undergone stem cell transplantation, routinely receive irradiated blood products from the time of initial diagnosis.

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