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The Humane Society of the United States (HSUS) held a workshop in August 2002 in order to develop recommendations for minimizing pain and distress associated with polyclonal antibody (Pab) production. A small group of experts in the fields of antibody production, animal welfare, in vitro alternatives, and/or regulatory compliance participated in the roundtable discussion. The workshop was a scientifically based meeting, and recommendations were based on the extensive experience of the workshop participants as well as published literature regarding the relevant issues.

Participants recognized that insufficient attention has been paid to animal welfare aspects of Pab production, in part because this technique typically is a small part of larger research projects and is not, per se, directly related to the hypothesis being investigated. This lack of attention, as well as the pain and distress associated with Pab production, has led to our focus on this specific issue. Additionally, information in the published literature regarding Pab production varies greatly, further prompting the need to determine and harmonize recommendations.

Antibodies are produced by injecting an adjuvant (antigen) into the animal (human or nonhuman), thereby eliciting an antibody response by the immune system. The challenge involved in Pab production is to obtain high antibody yield while minimizing pain and distress to the animals. Several aspects of Pab production were considered by the group, including the determination of appropriate adjuvants, optimal volume of adjuvant per species, and optimal route of immunization; use of booster injections; consideration of available alternatives; and measurement of animal welfare. Each of these topics was considered in regard to minimization of pain and distress, and recommendations were generated. The participants also briefly discussed monoclonal antibody (Mab) production and corresponding alternatives.

The workshop resulted in both general and specific recommendations. General recommendations addressed outsourcing to Pab suppliers; increasing and improving training; increasing consideration of alternative production techniques; improving pain and distress assessment via score sheets; harmonizing guidelines; keeping abreast of and incorporating recent developments; minimizing the number of animals used when possible; and including relevant Pab production information in published papers. Some of the specific recommendations addressed were using the chicken egg yolk technique as a refinement and reduction procedure; choosing an adjuvant that produces high antibody yield while minimizing pain and distress; considering the use of Freund’s complete adjuvant (FCA) for the first injection; using the smallest volume of adjuvant possible; and determining appropriate use of booster injections. Finally, areas in which additional research is needed were discussed—such as proper pain and distress assessment, formulation of new adjuvants, and examination of the roles that pain and enrichment may play in Pab production. The recommendations from this workshop will be widely distributed in order to press the debate on this issue and to increase attention to the pain and distress associated with Pab production.