Multiple immunoassay in a single animal: a practical approach to immunotoxicologic testing.

A battery of immunoassays were developed for the rat which measured the major arms of the immune system, namely, humoral immunity, cell-mediated immunity (CMI), and macrophage function. Humoral immunity was assessed by the enzyme-linked immunosorbent assay (using keyhole limpet hemocyanin as antigen). CMI was measured by delayed-type hypersensitivity to heat-aggregated bovine serum albumin using a footpad swelling technique. Macrophage function was assessed by measuring the ability of macrophages to phagocytize sheep red blood cells in vitro. The feasibility of performing all three immunoassays in the same animal was investigated by treating groups of rats with all combinations of antigenic exposure used to induce each type of response. Multiple antigenic treatment regimens did not significantly alter responses to individual antigens used in this study. Animals exposed to the concurrent antigen treatment regimens remained sensitive to immunosuppressants. These data suggest that multiple immunoassays can be successfully performed utilizing a single animal which has been concurrently treated with different antigens. The inclusion of additional assays into this protocol and the efficacy to immunotoxicologic testing is discussed.