Читать книгу Transfusion Medicine - Jeffrey McCullough - Страница 148

Procedures for the fractionation of plasma were developed during the 1940s in response to World War II (see Chapter 1). A large pool of plasma, often up to 10,000 L or 50,000 donor units, is processed using cold ethanol fractionation. In cold ethanol, different plasma proteins have different solubilities, which allow their separation. This large‐scale separation and manufacturing process results in the isolation of several proteins from plasma that are prepared for therapeutic use. These are called “plasma derivatives” (Table 5.10). The major derivatives have been albumin, immune serum, immune globulin, and coagulation factor VIII concentrate. Until the late 1980s, techniques were not available to sterilize some blood derivatives after manufacture. Thus, because of the large number of units of donor plasma in each pool, the chance of contamination of the pool with viruses (i.e., hepatitis and HIV) was high and the risk for disease transmission from these nonsterilized blood derivatives was high (see Chapter 17). This risk was accentuated because much of the plasma that serves as the raw material for the manufacture of blood derivatives was obtained from paid donors, a group known to provide blood with an increased likelihood of transmitting disease [93, 94]. Initially, only albumin and immune globulin carried no risk for disease transmission—albumin because it was sterilized by heating, and immune globulin because none of the known infectious agents was contained in that fraction prepared from the plasma. Because of the recognition of the high risk for disease transmission by coagulation factor concentrates, methods were developed to sterilize them [95, 96].

Concerns arose about the possible transfusion transmission of the agent responsible for variant Creutzfeldt–Jakob disease because this infectivity is not inactivated by most conventional methods. Fortunately, it appears that the prions associated with variant Creutzfeldt–Jakob disease do not partition with the therapeutic proteins during plasma fractionation [97, 98].