Antibodies against Entamoeba histolytica antigens in sera from individuals with amoebiasis of different localization.

The over-all contents and relative component composition of Entamoeba histolytica antigens in abscess fluids and in extracts of cultured amoebae, strain NIH 200, were studied by antigen-catching EIA, counterimmunoelectrophoresis (CIE) and immunoblotting techniques. The antigen contents of liver abscess fluid were determined semiquantitatively by the antigen-catching EIA in four cases. In CIE against a standard "diagnostic" extract of cultured amoebae, sera from cases of acute amoebic liver abscess gave 4-5 precipitation lines while sera from cases of intestinal amoebiasis gave at most 3 lines. In immunoblotting tests with the same antigen, intestinal cases gave blotting bands in the intermediate molecular weight range (25-99 kD) while acute abscess cases, in addition, gave bands in the high (100-175 kD) and low (= less than 25 kD) molecular weight range. These serological differences between clinical forms of amoebiasis were more definite when using amoeba abscess fluid as antigen. Amoeba antigens in high concentrations could be demonstrated in amoeba abscess fluids with all methods employed. In immunoblotting experiments abscess fluids generally gave stronger and more numerous bands with anti-amoeba antibody-containing sera than did the standard "diagnostic" antigen from cultured amoebae. Especially the abscess fluids gave with sera from acute abscess cases a number of prominent bands in the low molecular weight range (less than 25 kD). The experiments in this study were performed with crude amoebic extracts, which contained a multitudes of antigenic components and a still greater diversity of antigenically inert proteins.(ABSTRACT TRUNCATED AT 250 WORDS)