Reversed passive haemagglutination systems for the estimation of tetanus toxins and antitoxins

Preserved sheep erythrocytes sensitized with tetanus antitoxins of varying purity have been used as the indicator in the estimation of tetanus toxins and antitoxins.

Suspensions giving good agglutination patterns were produced using unrefined serum from well-immunized horses, pepsin-refined serum and preparations of γ-globulin. The most stable preparation was a freeze-dried suspension that had been sensitized with immune γ-globulin.

When these suspensions were used for the estimation of tetanus toxic filtrates by direct agglutination and tetanus antitoxins by haemagglutination inhibition the results in both cases were in close aggrement with the in vivo values as estimated by the mouse test at the 0.1 L+ level.