Neutrophil products and alterations in epithelial junctional proteins: prevention of artifactual degradation

• Published in: Journal of immunological methods Vol. 239; no. 1; pp. 45 - 52
• Main Authors: Ginzberg, Hedy, Shannon, Patrick, Downey, Gregory P
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 26.05.2000; Elsevier
• Subjects: Adherens junctions; beta Catenin; Biological and medical sciences; Cadherins - metabolism; Cells, Cultured; Cytoskeletal Proteins - metabolism; Diverse techniques; Epithelial Cells - metabolism; epithelial junctional proteins; Epithelium; Fixation; Formates; Formic acid; Fundamental and applied biological sciences. Psychology; Humans; Membrane Proteins - metabolism; Microscopy, Fluorescence - methods; Molecular and cellular biology; Neutrophil; Neutrophils - cytology; Neutrophils - metabolism; Phosphoproteins - metabolism; Tight junctions; Trans-Activators; Tumor Cells, Cultured; Zonula Occludens-1 Protein; Adherens junctions; Fixation; Neutrophil; Tight junctions; Epithelium; Formic acid; Histological fixation; Endothelial cell; Sample preparation; Cell cell interaction; Tight junction; Artefact; Adhesion; Protein
• ISSN: 0022-1759; 1872-7905
• DOI: 10.1016/S0022-1759(00)00166-6

Recent reports of disruption of endothelial cell adherens junction proteins during neutrophil adhesion and transmigration have been challenged as being partly due to post-fixation artifactual release of neutrophil-derived proteases. In this study we examined alterations in the epithelial junctional complex during neutrophil adhesion. Using standard fixation protocols, neutrophil addition to epithelial monolayers resulted in gross disruption of apical junction protein immunofluorescence. However, the inclusion of a post fixation incubation step with formic acid resulted in epitope preservation. These observations indicate that neutrophil derived products, likely proteases, remain active despite prolonged exposure to conventional fixatives. This may result in diffuse and artifactual loss of epithelial junctional protein immunofluorescence. Formic acid prevents this loss of epitope staining and may be considered as an agent to preserve protease-sensitive endothelial or epithelial immunoreactivity.