[Axenic and polyxenic antigens of Entamoeba histolytica in the diagnosis of human amebiasis].

A comparison of the antigenic activity of soluble extracts of Entamoeba histolytica kept in axenic and polyxenic cultures is undertaken. Special care was kept so as to keep the protein native structure unharmed. Chromatographic separation at G-200 was performed, and three fractions were obtained and submitted to reactions with the sera of 10 patients with a proven diagnosis of amebic hepatic abscess, 5 patients with amebic dysentery from whom the protozoon was isolated and cultured from feces, and finally from 10 control subjects. The ELISA technique was employed to detect the levels of antibodies, using the raw, soluble, antigens and the chromatographic ones which were obtained. The specificity of the antibodies was analyzed with I.E.E., and a spectrophotometric reading of the raw, soluble, antigens adsorbed was performed by chromatographic affinity, with sepharose columns joined with purified immunoglobulins extracted from the seric combinations of each one of the studied individuals. Our results prove that the values of D.O. of the ELISA, when a soluble SAX I fraction is used, are statistically significant when compared with the raw, soluble, antigen, and this fraction allows discrimination between patients with intestinal and extraintestinal amebiasis. Specific reactivity was demonstrated by antigenic, proteic, bands opposed to the sera from patients with hepatic abscesses, with the use of axenic, soluble antigen, as well as at least one proteic band which reacts with the sera of patients with amebic dysentery. Proteic bands that react indistinctly with immunoglobulins from the three studied groups were demonstrated. The polyxenic, soluble extract demonstrated a proteic band recognized by the sera from patients with amebic dysentery.