Effects of tannic acid on antigenicity and membrane contrast in ultrastructural immunocytochemistry.
We have modified our previous method for immunogold staining of unosmicated, plastic-embedded tissue by addition of tannic acid as a post-fixative to increase membrane contrast. Overall cell ultrastructure and organelle membranes, in particular, appeared well preserved after this treatment. We evaluated quantitatively the effect of tannic acid on the antigenicity of several membrane proteins in rat liver and intestine. For all antigens tested, significant antigenicity was retained on both intracellular and plasma membranes. However, the level of antigenicity decreased with increased concentrations of tannic acid. This effect was most apparent on the apical and basolateral membranes of hepatocytes and on the apical membrane of enterocytes, surfaces that had been in direct contact with the tannic acid fixative. The results indicate that when low concentrations of tannic acid are employed, this method yields greatly enhanced membrane contrast while preserving sufficient antigenicity to facilitate the ultrastructural localization of many membrane and other antigens.
Department of Biology, University of Virginia, Charlottesville 22901.
M A
MA
Berryman
W R
WR
Porter
R D
RD
Rodewald
A L
AL
Hubbard
D000818:Animals; D000941:Antigens / Q000276:immunology*; D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D005260:Female; D047348:Hydrolyzable Tannins; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000648:ultrastructure; D008099:Liver / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains; D011961:Receptors, Fc / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism; D016707:Tissue Fixation
D000941:Antigens; D037263:Asialoglycoprotein Receptor; D001212:Asialoglycoproteins; D047348:Hydrolyzable Tannins; D011961:Receptors, Fc; D011971:Receptors, Immunologic; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4