QUANTITATION OF ANTITETANUS AND ANTI-DIPHTHERIA ANTIBODIES BY ENZYMO-IMMUNOASSAY - METHODOLOGY AND APPLICATIONS

We have developed enzymoimmunoassays (EIA) for the quantitation of antibodies (Ab) to tetanus and diphtheria toxoids (TT, DT) using Immulon I plates coated with the appropriate toxoid. A preparation of human tetanus immunoglobulin with a known concentration of anti-TT Ab was used as calibrator of the anti-TT antibody assay. The assay of anti-DT Ab is calibrated with a pool of human sera whose anti-DT Ab concentration was determined by quantitative immunoelectrophoresis, using a horse anti-DT with known Ab concentration as calibrator. A peroxidase-conjugated anti-human IgG was used in both assays. ABTS was used as substrate, and the reaction was stopped after 1 min incubation with citric acid and the OD measured at 414 nm on a V(max) reader. The assays have been applied to a variety of clinical situations. In patients suspected of having tetanus, the quantitation of antibodies has been helpful in establishing a diagnosis. In patients with a history of hypersensitivity to tetanus toxoid, verification of the levels of anti-TT antibody may prevent unnecessary and potentially harmful immunizations. The assays have also been used for the diagnostic evaluation of the humoral immune response to TT and DT, both in pediatric patients and in immuno-suppressed patients. Several non-responders have been detected, and we have recently used the assay to monitor the effects of fish oil administration on the humoral immune response. Finally, the sensitivity of the assay for anti-TT antibody has been proven to be adequate for the assay of anti-TT Ab produced in vitro by stimulated human B cells. In conclusion, the assay of anti-TT and anti-DT antibodies by EIA is relatively simple and has a variety of clinical and research applications.