These data suggest that RCCs and FFP produced from WB that has been stored at ambient temperature with or without active cooling are of acceptable quality compared with those produced using current standard methods in the United Kingdom.

Summary. The aim of this study was to evaluate the quality of leucodepleted (LD) fresh-frozen plasma (FFP) produced using one of five whole blood filters (Baxter RS2000 & RZ2000, NPBI T2926, Macopharma LST1 and Terumo WBSP) or two plasma filters (Pall LPS1 and Baxter FGR7014). Whole blood or plasma was filtered within 8 h of collection at an ambient temperature. Samples were taken pre-and post filtration for analysis of coagulation factors and complement activation (n 7±12 for each type of filter). All filtered units (209±286 ml) contained , 5 Â 10 6 residual leucocytes and , 30 Â 10 9 /l platelets. Statistically significant losses of factors V, VIII, IX, XI and XII and increases in markers of coagulation activation were observed (0±21%), which were dependent on filter type. None of the filters had a significant effect on von Willebrand factor (VWF) multimeric distribution or the activity of VWF and factors II, VII or X. The effect on levels of C3a appeared to be related to the filter surface charge: positively charged filters resulted in C3a generation, whereas negatively charged resulted in C3a removal. None of the observed changes are likely to be clinically significant unless subsequent processing of plasma (such as pathogen inactivation) results in further losses of coagulation factors.

An anti-idiotypic antibody has been raised which recognizes human immunoglobulins with cold agglutinin activity of anti-I/i specificity. The pattern of reactivity of the antibody indicates that the structural basis for the epitope is located in the VH4-21 gene segment of the VHIV family, which is preferentially utilized by these cold reactive antibodies. Using this antibody, epitope expression was investigated in a panel of 72 human monoclonal allo-antibodies specific for human blood group antigens, as compared with a control panel of 39 randomly selected human monoclonal IgM antibodies of unknown specificities. The anti-blood group panel included 44 IgM and 28 IgG monoclonal antibodies against a variety of blood group antigens including the A antigen, Rh C, c, D, E, e, G antigens, and the Kidd antigens Jka and Jkb. The epitope was expressed by 64% (28/44) of the IgM anti-blood group antibodies and by 21% (6/28) of the IgG antibodies, but by only 7.7% (3/39) of the control IgM antibodies. These data indicate that the human alloimmune response to blood group antigens is biased in the use of VH gene families, with a preference for the VH4-21 gene segment of the VHIV family, or closely related gene segments. The fact that this mirrors the findings for the autoimmune cold agglutinins suggests a link in immunoglobulin gene usage between antibodies against structurally diverse antigens on the red cell surface.

Our results indicate that replacing plasma in PC with unmodified PASIII for storage results in higher levels of platelet-derived cytokines in PC. Furthermore, it appears that the nature of the medium used for storage of PC has a significant impact on platelet activation and cytokine levels of the PC. These implications should be taken into account when considering replacement of plasma with PAS.

Anti-I/i reactivity is common among IgM Rh system MoAbs and is shown only by the V4-34-encoded subset. This finding has implications for the use of MoAbs for Rh system typing of blood.