Fresh Frozen Plasma Contains Viable Progenitor Cells – Should We Irradiate?

While it is well established [I] that cellular blood products may be the cause of transfusion-associated graft-versus-host disease (TAGVHD), acellular products such as fresh plasma, fresh frozen plasma (FFP), and cryoprecipitate are widely regarded as containing too few immunocompetent cells to pose a serious threat even to the immunocompromised recipient. Only one report has identified passenger leukocytes in fresh plasma as the likely cause of TAGVHD [2]. The freeze-thaw procedure required for FFP and cryoprecipitate makes it even more unlikely that such products may contain sufficient numbers of viable lymphocyted and progenitor cells. The minimal dose of immunocompetent cells needed to induce TAGVHD is not fully established but a figure of lo7 lymphocytes per kilogram has been suggested, based on animal studies [3]. FFP is obtained from whole-blood donations after an initial spin to create platelet-rich plasma, followed by a second spin to create platelet concentrate. FFP is expressed after the second spin, leaving approximately 50 ml plasma with the platelet component and stored below -18°C. We looked at nucleated cell counts, viability, and colony-forming capacity in cells isolated from a series of FFP. FFP was transferred to plastic tubes and spun, and all sedimented cells were collected and resuspended in RPMI-1640 medium. Viability was assessed by trypan blue dye exclusion. Cell concentration was adjusted to lo6 per ml and seeded onto Terry Fox complete methyl cellulose media fortified with interleukin-3, stem cell factor and human placcnta conditioning media. Plates were incubated at 37°C in a humid atmosphere containing 5% C 0 2 . Colonies were counted after 2 weeks of incubation. Results are shown in table 1. Fresh Frozen Plasma Contains Viable Progenitor Cells Should We Irradiate?