[Industrial pasteurization of plasma and criteria of quality]

The approach followed in the design of a large-scale pasteurization treatment (60 degrees C for 10 hours in the liquid state) of fresh frozen plasma is presented. Various aspects thought to influence the viral safety of such a product are discussed. They are based largely upon the fact that, although it is subjected to a specific viral inactivation treatment, this plasma does not benefit from any fractionation steps known to participate in the potential elimination of infectious agents during the manufacture of plasma derivatives. Consequently, the plasma is obtained from regular plasmapheresis donors, and the plasma donations used to make the pool must be negative for anti-HIV-1 and -2, anti-HCV, anti-HBc, anti-HTLV-1 and -2, HBs antigen and parvovirus B19 antigen, and have a normal level of ALT. The batch size is limited to 100 plasma units to limit the potential infectious risk associated with very large batches, especially if an infectious agent, resistant to pasteurization, is present. Pasteurization has been chosen for this procedure, as applied to plasma derivatives, has been shown to inactivate a broad spectrum of viruses, both enveloped and non-enveloped. The process is relatively simple. The frozen plasma units are opened, and the plasmas are mixed and thawed at 30 degrees C to avoid the formation of cryoprecipitate. The liquid plasma is transferred to a sterilized container and stabilizers are added. The mixture is then transferred to the pasteurization unit to be heat-treated at 60 degrees C for at least 10 hours under gentle mixing. Following cooling, the mixture is ultrafiltered to eliminate the stabilizers and to concentrate the plasma pool to its initial volume. The plasma is sterile-filtered, then dispensed into bottles and frozen. Virus validation of this pasteurization process, carried out by independent virology laboratories, have confirmed the ability of the process to inactivate more than 4 to 6 logs of non-enveloped or enveloped, DNA or RNA, viruses, including HIV-1 and Sindbis virus, in less than 5 hours of heat-treatment. The biological characteristics of the pasteurized plasma include a good preservation (75 to 95%) of the activity of clotting factors, including FI, FV, FVIII, FXI, and FXIII, and protease inhibitors. The overall clottability of the plasma, as expressed by the APTT, is almost unchanged.(ABSTRACT TRUNCATED AT 400 WORDS)