Traditional polyclonal antibody preparations

Polyclonal antibody preparations have been used for several decades to induce passive immunization against infectious diseases and other harmful agents, particularly toxins. The antibody preparations are usually administered by direct i.v. injection. While this affords immediate immunological protection, its effect is transitory, usually persisting for only 2-3 weeks (i.e. until the antibodies are excreted). Passive immunization can be used prophylactically (i.e. to prevent a future medical episode) or therapeutically (i.e. to treat a medical condition that is already established). An example of the former would be prior administration of a specific anti-snake toxin antibody preparation to an individual before they travel to a world region in which these snakes are commonly found. An example of the latter would be administration of the anti-venom antibody immediately after the individual has experienced a snake bite. 

Pharmaceutical biotechnology concepts and applications Gary Walsh 2007 John Wiley Sons, Ltd ISBN 978 0 470 01244 4 (HB) 978 0 470 01245 1 (PB) 

Antibody preparations used to induce passive immunity may be obtained from either animal or human sources. Preparations of animal origin are generally termed antisera , and those sourced from humans are called immunoglobulin preparations . In both cases, the predominant antibody type present is IgG. 

The blood is collected using an aseptic technique into sterile containers. It can then be allowed to clot with subsequent recovery of the antibody-containing antisera by centrifugation. Alternatively, the blood may be collected in the presence of heparin, or another suitable anticoagulant, with subsequent removal of the suspended cellular elements, again by centrifugation. In this case, the resultant antibody-containing solution is termed plasma . 

Although specific antisera have proven invaluable in the treatment of a variety of medical conditions (Table 13.1), they can also induce unwanted side effects. Particularly noteworthy is their ability to induce hypersensitivity reactions some such sensitivity reactions (e.g. serum sickness ) are often not acute, whereas others (e.g. anaphylaxis) can be life threatening. Because of such risks, antibody preparations derived from human donors (i.e. immunoglobulins) are usually preferred as passive immunizing agents. 

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