Primary antibody response to keyhole limpet hemocyanin in rat as a model for immunotoxicity evaluation.
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 (300microg/rat) or intravenous (300microg/kg) route in Sprague Dawley rats resulted in increased germinal center formation in the spleen and a robust anti-KLH IgM (70-388microg/ml) and IgG (230-470microg/ml) antibody response with peak detection on Days 5 and 14 post-immunization, respectively. Subcutaneous immunization with KLH (300microg/kg) resulted in a much weaker anti-KLH IgM and IgG (< or =20microg/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 (> or =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.
Gore
Elizabeth R
ER
Department of Safety Assessment, UE0359, GlaxoSmithKline Pharmaceuticals, Box 1539, King of Prussia, PA 19406, USA. elizabeth.r.gore@gsk.com
Gower
Jill
J
Kurali
Edit
E
Sui
Jui-Lan
JL
Bynum
Jane
J
Ennulat
Daniela
D
Herzyk
Danuta J
DJ
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects* / Q000276:immunology; D000941:Antigens / Q000008:administration & dosage / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005528:Foot; D006433:Hemocyanins / Q000008:administration & dosage / Q000276:immunology / Q000494:pharmacology*; D006614:Hindlimb; D006965:Hyperplasia / Q000209:etiology / Q000473:pathology; D007111:Immunity, Cellular / Q000187:drug effects* / Q000276:immunology; D016867:Immunocompromised Host; D007074:Immunoglobulin G / Q000032:analysis / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000032:analysis / Q000096:biosynthesis; D007165:Immunosuppression Therapy / Q000009:adverse effects; D007166:Immunosuppressive Agents / Q000145:classification / Q000633:toxicity*; D007267:Injections; D008297:Male; D023421:Models, Animal; D011650:Pulmonary Alveoli / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012141:Respiratory Tract Infections / Q000276:immunology / Q000473:pathology
D000941:Antigens; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007166:Immunosuppressive Agents; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin