Antigenicity of sub-cellular components of Entamoeba histolytica.

Antigencity of the sub-cellular components of axenic Entamoeba histolytica trophozoites was studied. The cells were disrupted by means of a glass-teflon homogeniser and sub-cellular components were prepared by stepwise differential centrifugation. Four fractions were obtained, namely the 350 g, 6500 g, and 100,500 g fractions and the cell sap. Components of the sedimented fractions were examined by phase contrast and electron microscopy. The antigenicity of each fraction was studied by two different methods:-(1) By extraction with 0.5% sodium deoxycholate followed by testing against the reference sera; (2) By demonstration of the loss of immunological activity of the reference sera after absorption with fractionated components. It was found that all 4 fractions had varying antigenic activities as measured in the indirect hemagglutination (IHA), the complement fixation (CF) and the immunoelectrophoresis (IEP) tests. With the extraction technique, the following results were obtained:- The highest IHA activity was found in the cell sap, whereas this activity in other fractions clustered at lower levels. In the CF test, the activities associated with all 4 fractions were similar. In the IEP test, the highest activity was found in the cell sap and the least activity in the 100,500 g fraction. With the absorption technique, slightly different results were obtained. Whilst in the IHA and the IEP test, the results were in concordance with the extraction technique, the CF activity was slightly different, since it was highest in the cell sap and least in the 100,500 g fraction.