Cellulose acetate membrane precipitin (CAP) test in amoebiasis using antigens from four different strains of Entamoeba histolytica

Abstract

A simple cellulose acetate membrane precipitin (CAP) test was evaluated against an immunoelectrophoresis (IEP) test using saline extract from 4 different strains (HK-9, HT-10, HT-12 and HT-31) of axenically grown Entamoeba histolytica as the antigens. All 81 sera from patients with amoebic liver abscess were positive in the IEP test against the antigens from all 4 strains. With the CAP test the number positive against antigens from HK-9, HT-10, HT-12 and HT-31 were 79, 77, 79 and 71, respectively. Sera from 100 blood donors were negative by both IEP and CAP tests against antigens from all 4 strains. Comparison between the number of precipitating bands demonstrated by either the IEP or CAP test showed that strain HT-12 was the best source of antigen in exhibiting a significantly greater number of precipitating bands; strain HT-31 was the poorest. The strain HT-10 was comparatively superior to strain HT-31 in the CAP test, whereas in the IEP test strains HK-9 and HT-31 were both inferior to strain HT-10.