Histochemical localization of sialylated glycoconjugates with Tritrichomonas mobilensis lectin (TLM).

A new sialic acid-specific lectin from the colonic parasite of squirrel monkeys Tritrichomonas mobilensis (TML) was tested on human and mouse tissues for histochemical staining properties. There were no substantial differences in reactivity between frozen and formalin fixed paraffin sections. TML staining was blocked by preincubation with sialic acid or by sialidase digestion. TML/anti-TML antibody histochemistry was identical with the TML-gold technique. The staining pattern was not blood group dependent. TML stained strongly the luminal membranes of normal vascular endothelium as well as endothelial neoplasms. Lymphatic vessels and capillaries of kidney glomeruli and lung alveolar septi were negative or only slightly positive. In parenchymatous organs luminal membrane positivity was dominant, preferably of cells lining ducts. Weak fine-granular cytoplasmic and basolateral membrane staining was also observed. Umbrella cells in transitional epithelium and basal layers of squamous epithelia showed strong reactivity with cell membranes. Mucin in respiratory epithelium was positive whereas gastrointestinal mucins failed to stain uniformly. Erythrocytes and most white blood cell types showed distinct membrane positivity. Acetylation or alkaline O-deacetylation of tissue sections did not substantially change TML reactivity. Oxidation, however, completely blocked TML staining except for respiratory epithelium and colonic mucin.