[Detection and titration of antitetanus antibodies using an automated passive hemagglutination method].

An automated reversed passive haemagglutination technique is described, using human erythrocytes sensitized by the chromic chloride method with higly purified tetanus toxoid. Such erythrocytes are agglutinated by the specific antibodies in a Technicon autoanalyzer. Clots are decanted, supernatant is hemolyzed and optical density is measured at 550 millimicron. Assay standards for comparison, ranging from 5 to 25 UI/ml, are prepared from human antitetanus immunoglobulins titrated by toxin neutralisation assay in mice. This method allows to screen donors' sera for presence of high titers of tetanus antibodies (larger than or equal to 5 UI) suitable for preparation of antitetanus immunoglobulins. 4,4% of donors have circulating antitetanus antibody levels corresponding to 5 UI/ml or more, by this method. The specificity of antibodies has been confirmed by the neutralisation assay in mice. The results obtained among 1.000 donors well agree with those of the counter-immuno-electrophoresis technique (C.E.P.). But, when, compared with C.E.P., the haemagglutination assay appears more objective, more quantitative and sensitive, and allows to get not only a rapid screening test but also a precise titration simultaneously.