Bio-Assay of Four Tetanus Toxoids (Aluminum Precipitated) in Mice, Guinea Pigs and Humans

Abstract

Summary A series of experiments are presented where the validity of an adequate bioassay of tetanus toxoids was tested by comparing the immunizing potency of the same four aluminum precipitated tetanus toxoids in mice, guinea pigs and humans. The mouse test was carried out in six laboratories using the same material and method. A three dose assay was performed challenging the animals with toxin fourteen days after immunization. Results obtained in all six laboratories agreed within the intra-assay error. One hundred and twenty-eight young adults who had not previously received tetanus toxoid were subdivided in eight groups of sixteen. Each group received either one of the four toxoids, in either of two doses. Antitoxin titres after 28 days were compared, with analysis of the four two-dose regression lines. The same number of guinea pigs received the identical treatments as the humans. Pools of serum for subgroups of eight were titrated for antitoxin. The relative potencies of the four toxoids to produce primary immunity in the three animal species agreed within the experimental error. In the guinea pigs and humans the response fourteen days after a second injection was also observed, and the relative potencies of the four toxoids to provoke the secondary reaction were comparable to those computed on the basis of primary stimulus. The assays based on secondary reaction are less precise than assays based on primary stimulus. The precision of assays based on primary immunity reaction is the same per individual whether mice, men or guinea pigs are used. Hence, the mouse assay is by far the least expensive.