Characterization of the T-dependent antibody response (TDAR) to keyhole limpet hemocyanin (KLH) in the Göttingen minipig

Abstract

Recently, there has been a renewed interest in the use of the minipig as an alternative to dogs and non-human primates for conducting toxicological assessments in non-rodent species. Since the T-dependent antibody response (TDAR) is one of the most widely-accepted assays used in the assessment of immunocompetence, the present study was undertaken to characterize the primary and secondary TDAR to keyhole limpet hemocyanin (KLH) in the Göttingen Minipig®. Following primary immunization with either 2 or 10mg KLH, anti-swine IgM and IgG ELISAs were optimized and individual animal responses were evaluated over time. Immunization with 10mg KLH on Day 0 promoted primary IgM responses that peaked 6-9 days after antigen administration, while primary IgG levels peaked on Day 13 or 14. Secondary IgG antibody levels (following secondary injection with 2mg KLH on Day 14) plateaued on Days 20-22. Anti-KLH antibody levels were decreased in minipigs treated with cyclophosphamide (CPS), a known immunosuppressant, at doses ranging from 12.5-50mg/kg/day, while antibody levels in animals treated with 2.5mg CPS/kg/day were similar to levels in saline-treated swine. These results demonstrate that the Göttingen Minipig® can be a useful alternative non-rodent species to the dog and the non-human primate for evaluating the TDAR to KLH in regulatory assessments of immunotoxicity.