Transfusion-associated graft-versus-host disease can be prevented by treating cellular blood products with gamma irradiation. A wide range of gamma irradiation dose levels has been used in routine practice. We used limiting dilution analysis, which measures clonable T cells, to assess the influence of 500 to 3,000 cGy of gamma irradiation delivered from a 137Cs source on T cells when delivered in situ to ADSOL- preserved red blood cell (RBC) units in blood bags. In a series of experiments using RBC units irradiated within 24 hours after collection, 1,500 cGy inactivated > 4 log10 of T cells; however, viable T cells were detected in all experiments. With 2,000 cGy, a > or = 4.7 log10 decrement in T-cell growth occurred in 7 of 8 experiments. With 2,500 or 3,000 cGy, no T-cell growth (> 5 log10 depletion) was detected. Comparable effects were observed with ADSOL-preserved RBC units in the standard PL 146 plastic container and in the recently developed PL 2209 plastic container. T-cell inactivation, as a function of gamma irradiation dose, was similar when either a 137Cs or a linear accelerator source was used. T cells isolated from ADSOL-preserved RBC units after storage for 7 and 21 days, although reduced in number as compared with a fresh unit stored for 24 hours, were viable, capable of proliferation, and susceptible to inactivation by gamma irradiation. Using a sensitive in vitro assay for T-cell proliferation, we found that a gamma irradiation dose of 2,500 cGy may be required to completely inactivate T cells in RBC units.

Hospitals are required by accrediting agencies to perform blood utilization review. Specific areas that must be addressed are the ordering, distribution, handling, dispensing, and administration of blood components. Monitoring the effects of transfusion on patients is also required. The format of the review process and the criteria for appropriate blood utilization must be developed by each institution. This article provides examples of areas that can be reviewed and procedures that may be used. However, the suggested laboratory values must not be interpreted as defining indications or criteria for transfusion. Each transfusion committee, or its equivalent, is responsible for developing its own institutional blood utilization procedures and audit criteria. Review and approval by the medical staff prior to implementation are essential. The procedures must also be reviewed and revised on a regular basis.

he Blood Products Advisory Committee of the Food and Drug Administration (FDA) recently recommended the approval of the use of solvent T and detergent treatment for fresh-frozen plasma (FFP). The FDA is expected to issue soon a license to VI.Technologies, Inc. (VITEX, New York, NY) to produce solventldetergent (SD)-treated plasma (SD plasma). Because an estimated 2 million units of plasma are transfused in the United States each year, the availability of an alternative blood component will likely have a significant impact on physician practices and on the supply of, and demand for, FFP This report reviews issues surrounding the development of SD technologies for use in virus inactivation, current clinical data relevant to the use of SD plasma, and answers to some commonly asked questions. The review is intended not to establish a standard or requirement for the use of FFP or SD plasma, but to provide background information for medical staffs as they consider transfusion alternatives. Development of guidelines or standards for voluntary compliance will require additional clinical data.Currently, most FFP is prepared in blood centers as a by-product of whole-blood processing, although FFP can also be prepared by plasmapheresis. FFP is a relatively safe biologic; its overall risk is estimated at 7.5 adverse events per 10,000 units transfused and 3.7 adverse events per 1,000 ABBREVIATIONS: AHF = anti-hemophilic factor; FDA = Food and Drug Administration; FFP = fresh-frozen plasma; HAV = hepatitis A virus; HBV = hepatitis B virus; HCV = hepatitis C virus; HIV = human immunodeficiency virus; IU = International units; SD = solventldetergent (treatment); TNBP = tri(n-buty1)phosphate; lTP = thrombotic thrombocytopenic purpura.From the American Association of Blood Banks Ad Hoc Committee on SolventlDetergent-Treated Plasma.

he use of irradiated blood components to prevent graft-versus-host disease in susceptible patients has increased dramatically in the past sev-T eral years. Irradiation eliminates the proliferative capacity of lymphocytes present in red cell, platelet, and freshly collected plasma component^.'-^ After penetrating blood components, the photons delivered by a radiation beam cause the formation of electrically charged particles or secondary electrons. These electrons damage the DNA of lymphocytes, either by direct interaction or by reacting initially with cell water to form free radicals. The damaged lymphocytes are unable to proliferate in the host and therefore cannot mediate transfusion-associated graft-versus-host disease.The photons used to irradiate blood components are generated by one of two methods, using either a gamma-ray beam or an x-ray beam. Gamma rays contain photons generated by the decay of radioactive isotopes such as cesium-137 (Cs-137) or cobalt-60 (co-60). These isotopes can be positioned inside lead-enclosed chambers in dedicated irradiation instruments. X-rays are photon beams generated mechanically by teletherapy devices that accelerate electrons to very high speeds, directing them to a metallic target such as tungsten and generating a photon beam as a result of this collision. The linear accelerator is an example of the kind of instrument that generates x-rays as an irradiation source. There are no physical differences between gamma rays and x-rays; they exhibit the same radiation characteristics and damage lymphocytes in a similar manner.4 ABBREVIATIONS: LDA = limiting dilution analysis; MLC = mixed lymphocyte culture; Mosfet = metal-oxide silicon field effect transistors; TLD = thermoluminescent dosimeter.

Platelet concentrates intended for transfusion to immunosuppressed patients are irradiated to minimize transfusion-induced graft-versus-host disease. Because few reports describe how irradiation influences stored platelets, the authors studied whether 5000 rad of gamma irradiation, the maximum dose currently used clinically, altered platelets in vitro. Platelet concentrates were stored for either 1 day or 5 days in plastic (PL 732) containers before gamma irradiation. One unit of a pair of identical platelet concentrates was irradiated; the second unit served as a control. Irradiation did not alter platelet morphology, mean platelet volume, expression of platelet-factor-3 activity, response to hypotonic stress, extent of discharge of lactate dehydrogenase, release of beta-thromboglobulin, formation of thromboxane B2, nor the ability to undergo synergistic aggregation. The lack of any substantial change was observed whether the platelet concentrates were stored initially for either 1 day or 5 days. These results suggest that stored platelets are not altered deleteriously by irradiation with 5000 rad.