Cell surface carbohydrates in proliferative epidermal lesions. II. Masking of peanut agglutinin (PNA) binding sites in solar keratoses, Bowen's disease, and squamous cell carcinoma by neuraminic acid.

Seventy-six skin biopsies of proliferative lesions were studied by using 4 different lectins and an avidin-biotin-peroxidase complex. In solar keratosis, Bowen's disease and squamous cell carcinoma, malignant-appearing keratinocytes exhibited loss of membrane staining with Concanavalia ensiformis agglutinin (Con A), but revealed cytoplasmic staining. When incubated with peanut agglutinin (PNA), the malignant keratinocytes did not stain. However, the PNA binding sites were not absent, but masked by sialic acid. Following cleavage of the sialic acid with neuraminidase, free PNA binding sites could be demonstrated in the plasma membranes. In contrast, the keratinocytes in keratoacanthomas showed membrane staining with Con A and also contained free PNA binding sites. These histochemical findings confirm and extend our earlier observations regarding cell surface carbohydrates in premalignant and malignant epidermal lesions.