Primary antibody response to keyhole limpet hemocyanin in rat as a model for immunotoxicity evaluation

• Published in: Toxicology (Amsterdam) 2004-04, Vol.197 (1), p.23-35
• Main Authors: Gore, Elizabeth R., Gower, Jill, Kurali, Edit, Sui, Jui-Lan, Bynum, Jane, Ennulat, Daniela, Herzyk, Danuta J.
• Format: Article
• Language: English
• Subjects: Animals; Antibody Formation - drug effects; Antibody Formation - immunology; Antigens - administration & dosage; Antigens - pharmacology; Biological and medical sciences; ELISA; Enzyme-Linked Immunosorbent Assay; Female; Foot; General aspects. Methods; Hemocyanins - administration & dosage; Hemocyanins - immunology; Hemocyanins - pharmacology; Hindlimb; Hyperplasia - etiology; Hyperplasia - pathology; Immunity, Cellular - drug effects; Immunity, Cellular - immunology; Immunocompromised Host; Immunoglobulin G - analysis; Immunoglobulin G - biosynthesis; Immunoglobulin M - analysis; Immunoglobulin M - biosynthesis; Immunosuppression; Immunosuppression - adverse effects; Immunosuppressive Agents - classification; Immunosuppressive Agents - toxicity; Immunotoxicity; Injections; keyhole limpet hemocyanin; KLH antibodies; Male; Medical sciences; Models, Animal; Pulmonary Alveoli - pathology; Rat; Rats; Rats, Sprague-Dawley; Respiratory Tract Infections - immunology; Respiratory Tract Infections - pathology; Toxicology
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/j.tox.2003.12.003

To address current regulatory expectations on immunotoxicity testing of new chemicals, we describe an animal model that measures the primary antibody response to the T-cell dependent antigen, keyhole limpet hemocyanin (KLH). Single immunization with KLH by either footpad (300 μg/rat) or intravenous (300 μg/kg) route in Sprague Dawley rats resulted in increased germinal center formation in the spleen and a robust anti-KLH IgM (70–388 μg/ml) and IgG (230–470 μg/ml) antibody response with peak detection on Days 5 and 14 post-immunization, respectively. Subcutaneous immunization with KLH (300 μg/kg) resulted in a much weaker anti-KLH IgM and IgG (≤20 μg/ml) antibody response with no detectable increase in splenic germinal center formation. The utility of a rat KLH immunization model in detecting immunosuppression was evaluated with the known immunosuppressive drugs: cyclosporin, azathioprine and prednisolone. Rats, treated with drug at a maximum tolerated dose, were immunized with KLH by footpad or intravenous injection and serum samples were collected at various intervals up to 2 weeks post-immunization. Additional study parameters included terminal body weight, hematology and/or histopathology. All three drugs inhibited the IgM (60%) and IgG (≥90%) antibody responses in the absence of overt toxicity based on evaluation of the standard toxicology parameters. In conclusion, measurement of a rat primary antibody response to KLH by ELISA is a reliable and readily standardized method for assessing immunotoxicity of pharmaceuticals.