Solid-phase enzymoimmunoassay of antitetanus toxoid antibodies

A solid-phase enzymoimmunoassay (EIA) for antitetanus toxoid antibodies has been developed using activated agarose beads as the solid phase to which tetanus toxoid was covalently attached. The resulting EIA proved to be remarkably free of interference due to nonspecific absorption of reactants to the solid phase. The lower limit of detection for the assay was 0.008 U/ml of antibody. Reproducibility studies showed a satisfactory degree of consistency with coefficients of variation of 4.8% (within run) and 6.6% (run-to-run). This assay has been applied successfully to the evaluation of the humoral response to tetanus toxoid in both normal and immunocompromised individuals and it has sufficient sensitivity to determine serum levels of antitetanus antibody above the accepted protective limit of 0.01 U/ml.