Changes in the Affinity of Phosphotungstic Acid and Positively Charged Colloidal Particles for the Surfaces of Malignant Human Transitional Epithelium of the Urinary Bladder1

Phosphotungstic acid at low pH and colloidal iron hydroxide have been used to stain sialic acid residues at the surfaces of the transitional epithelium that covers the human urinary bladder. The staining of surfaces of normal epithelium was compared in the electron microscope to staining of surfaces of cells from noninvasive Grade I transitional cell carcinomas and from higher grades of invasive transitional cell carcinomas. Surfaces of normal epithelium and epithelium within the very-well-differen tiated Grade I transitional cell carcinomas exhibit similar levels of affinity for each stain. The surfaces of cells of higher grade invasive bladder carcinomas exhibit about a 40% reduction in affinity for the stains. Also, the interdigitations of the plasma membranes of epithelium from normal biopsies and Grade I carcinomas are absent in the invasive carcinomas. These observations indicate that surface sialic acid may have a role in intercellular adhesion and in stabilizing some surface structures of cells.