EVIDENCE FOR THE EXISTENCE OF GANGLIOSIDE MOLECULES IN THE ANTIGEN OFENTAMOEBA-HISTOLYTICA

Gangliosides were found to be present in Entamoeba histolytica. They w ere extracted from lyophilized trophozoites of the pathogenic strain H M-1:IMSS and purified by high performance thin-layer chromatography. T wo resorcinol-positive bands, comigrating with GM2 and GD1a were demon strated, revealing the existence of ganglioside molecules in Entamoeba histolytica. The GM2 content, determined as lipid-bound sialic acid, was 1.5 mu g/10(8) amoebae, the content of the GD1a comigrating band w as 0.32 mu g/10(8) amoebae. The identity of the GM2 comigrating band w as confirmed by TLC immunostaining, using the monoclonal anti-GM2 anti body GMB28. Furthermore, six out of ten anti-amoeba positive sera sele ctively reacted with the GM2 comigrating band, as repealed by immunost aining on TLC plates. Absorption tests revealed that preincubation of anti-amoeba positive sera with standard GM2 was followed by a signific ant decrease in the reaction with amoeba trophozoites by indirect immu nofluorescence. These results demonstrate that a GM2 comigrating compo nent of Entamoeba histolytica may be one of the antigens responsible f or the appearance of circulating antibodies in patients with amoebiasi s.