ENTAMOEBA-HISTOLYTICA - LOCALIZATION OF A 30-KDA CYSTEINE PROTEINASE USING A MONOCLONAL-ANTIBODY

We produced a monoclonal antibody against a major cysteine proteinase of 30 kDa from trophozoites of Entamoeba histolytica strain HM1:IMSS. The specificity of the monoclonal antibody was confirmed by specific i nhibition of azocasein digestion and by electrophoretic analysis, in t he presence of sodium dodecyl sulfate or on a substrate gel, of the an tigen precipitated by the antibody. Immunofluorescent staining of trop hozoites with the monoclonal antibody revealed heterogeneity in the in tensity of whole cell fluorescence and subcellular localization of the stain. The latter was also observed in trophozoites, which were stain ed by conventional immunohistochemical methods, from experimental live r abscesses in hamsters. Ultrastructural analysis showed antigen distr ibuted mainly in clear amorphous zones in the cytoplasm, which were no t limited by a visible membrane. Proteinases are translocated from the se compartments to phagocytic vacuoles after trophozoites ingest eryth rocytes, suggesting that these regions might be a lysosomal equivalent of this Primitive eukaryotic cell. (C) 1996 Academic Press, Inc.