Serology with polysaccharides of Entamoeba histolytica

The immunochemical activity of a polysaccharidic antigen derivated from E. histolytica was studied. This polysaccharide was tested by means of counterimmunoelectrophoresis (CIE) and radial immunodiffusion (IDR) against sera from patients with diagnosis of intestinal and hepatic amebiasis. In order to perform a test most significative to the problem sera, these were submitted previously to passive hemagglutination, CIE and IDR with total ameba antigen. In hepatic amebiasis it can be observed that the CIE done with commercial antigen is practically negative in all cases; incontrast, the test performed with total antigen was positive in almost all the cases. Passive hemagglutination with sheep red blood cells, tanned and sensibilized with total ameba antigen gave very high titers when the problem was amebic hepatic abscess, and very low when the problem was intestinal amebiasis. Counterimmunoelectrophoresis and radial diffusion were negative with polysaccharidic antigen in all the studied sera.