The influence of various fixatives on the immunohistochemical demonstration of a number of plasma proteins and oncofetal proteins in paraffin embedded material.

The influence of different fixatives on the antigenicity of alpha-fetoprotein (AFP), albumin, prealbumin, transferrin, ferritin, human chorionic gonadotropin (HCG), specific pregnancy beta 1-glycoprotein (SP1) and human placental lactogen (HPL) was studied. No single fixative was superior for all the antigens investigated. For intracellular antigens the best all-around fixatives were, however, 10% buffered formalin, 4% buffered paraformaldehyde, 10% formol-calcium and ethanol acetic acid (EA), cold processed. The preferable fixatives were for AFP: Bouińs fixative, B-5 and EA; for albumin: 10% formol-calcium; for prealbumin: Zambonis fixative and B-5; for transferrin: EA; for ferritin: 10% buffered formalin, 4% buffered paraformaldehyde, Lilliés fixative, Zambonis fixative and EA; for HCG: Bouińs fixative and B-5; for SP1: Lilliés fixative and EA; and for HPL: 4% buffered paraformaldehyde and Lilliés fixative. The preservation of extracellular antigens was different from the above mentioned intracellular ones. Thus fixation in 10% buffered formalin gave poor results while the coagulant fixatives such as Bouińs fixative, B-5 and Clelands fixative in general showed good preservation of the antigenicity of the extracellular antigens.