Kinetics of the Treponema immobilization reaction under improved conditions.

The demonstration by Nelson and Mayer (1949) of an antibody in syphilitic sera that immobilizes virulent Treponema pallidum in the presence of complement in vitro led to the development (Nelson and Mayer, 1949; Nelson and Diesendruck, 1951) of a T. pallidum immobilization (TPI) test for use in the case of individuals who might repeatedly give a positive reaction to other tests for syphilis but in circumstances suggesting that they might not in fact have the infection. Thus, TPI tests have been used to detect these biologic false-positive cases. However, there is a danger that other reactions, such as the destruction of complement, may lead to false-negative results, and it is generally recognized that provision against being misled by such results must be made: e.g., by making terminal tests for residual complement in the reaction mixtures. Other unwanted reactions, such as the clotting of test mixtures, may likewise interfere with the attainment of a decisive result. In view of such difficulties, wide variations in the constitution of reaction mixtures and in the conditions of maintenance have been introduced by various workers (Nelson and Mayer, 1949; Nelson and Diesendruck, 1951; Khan, Nelson, and Turner, 1951; Magnuson and Thompson, 1949; Thompson and Magnuson, 1951; Portnoy, Harris, and Olansky, 1953; Reyn and Nielsen, 1953; Wheeler, van Goor, and Curtis, 1954; Boak and Miller, 1954; Wilkinson, 1954; Nielsen, 1957). Both deliberate and inadvertent variations in test conditions have hindered comparison of the results, especially on a quantitative basis, since no adequate account of their influence has been available. Nielsen (1957) has made an extensive survey