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

A simple cellulose acetate membrane precipitin (CAP) test was evaluated against 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 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 IEP or CAP test showed that strain HT-12 was the best source of antigen in exhibiting significantly more 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 strain HK-9 and HT-31 were both inferior to strain HT-10.