Lectin-Gold Staining of Sialic Acid in Mesotheliomas and Pulmonary Adenocarcinomas

Abstract

Lectin-gold staining and electron microscopy techniques were used to determine the sialic acid patterns of epithelial mesotheliomas and pulmonary adenocarcinomas. Pulmonary adenocarcinomas and 4 malignant epithelial mesotheliomas from human tissue banks were used. Tissues were fixed in a mixture of 3% parafomaldehyde and 0.1% glutaraldehyde for 2 hr, dehydrated in increasing concentrations of ethanol, and embedded in Lowicryl K4M. Ultrathin sections on 150-mesh nickel grids were incubated with LimaxJavus lectin-gold (LFL-gl0), Sambucus nigrans lectin-gold (SNL-gl4), and Maackia amurensis lectin-gold (MAL-gl4). Both mesotheliomas and adenocarcinomas stained positively with (LFL-gl0) and (MAL-g14) and negatively with (SNL-gl4). Positive staining with MAL-g14 and an absence of staining with SNL-g14 show the terminal sialic acid linkage to D-galactose to be α2,3, rather than α2,6. Although, mesotheliomas stained with MAL-g14 had significantly more gold particles than did adenocarcinomas, the gold particle to cell membrane ratio was not different between the two. Therefore these lectins were not helpful in differentiating mesotheliomas and adenocarcinomas. (The J Histotechnol 20:31, 1997)

Keywords:

• electron microscopy
• lectin histochemistry
• mesothelioma