An immobilization test for amoebiasis.

The demonstration of antibodies in syphilitic sera that will immobilize Treponema pallidum (Nelson and Mayer, 1949) led Cole and Kent (1953) to investigate and demonstrate that immune rabbit sera were capable of immobilizing Entamoeba histolytica, and to suggest that sera from human cases of amoebiasis might show the same phenomenon. Their rabbit sera did not show immobilizing activity to a high titre but good immobilization of amoebae at single and twofold dilutions: further dilution of the sera led to a considerable fall in the immobilizing activity. In preliminary studies with sera from human cases of amoebiasis, these authors tested 13 sera, five of which showed some immobilizing activity in low dilution. The immobilizing effect appeared to be specific because 48 normal sera were without effect upon the amoebae. A further laboratory test for the diagnosis of amoebiasis would clearly be desirable owing to the unsatisfactory nature of the complement-fixation test. In this paper the results of applying an immobilization technique in parallel with a complement-fixation test are described.