Treponema pallidum immune-adherence and haemagglutination.

According to Nelson (1953), " the immune-adherence phenomenon" is concerned with the specific attachment which occurs between erythrocytes and micro-organisms which are sensitized by antibody (Ab) and Complement (C'). Measurements of immune-adherence (IA) may be performed by counting the Treponema pallida remaining in the fluid phase of reaction mixtures containing T. pallida, Ab, C', and erythrocytes. The counting of T. pallida under dark-field examination with high dry magnification is liable to error. Errors of counting are mainly due to the difficulty of placing between slide and coverslip an accurately calibrated volume of fluid mixture, and also from the unequal distribution of the T. pallida. Following Nelson's suggestions, we have studied a new procedure of IA by which readings are made easier and more reliable. This makes use of the haemagglutination induced by IA. This method shows the agglutination of erythrocytes attached to T. pallida sensitized with specific Ab and C'. The reading is similar to other haemagglutination tests.