Monoclonal antibodies in the diagnosis of epithelial premalignant lesions.

We investigated 14 oral lesions and 10 skin lesions with epithelial dysplasia and 10 oral squamous cell carcinomas by immunofluorescence staining using monoclonal antibodies to two blood group antigen A and B precursor structures: Type 2 chain H-antigen (Fuc alpha 1 leads to 2 Gal beta 1 leads to 4 GlNAc leads to R; A and B precursor) and N-acetyllactosamine (Gal beta 1 leads to 4 GlNAc leads to R; H precursor). Both precursors were in oral epithelium found on the cell membrane of basal cells; in skin they were present on spinous and granular cells. In 12 of the 14 oral lesions the H-antigen was found on all cells throughout the epithelium in higher titers than in normal adjacent epithelium. All 10 carcinomas showed an irregular distribution of H. Some tumor cells did not express H whereas others did. In all 10 skin lesions on the contrary the H-antigen was lost in the dysplastic epithelium. N-acetyllactosamine was found neither in premalignant or malignant oral nor in premalignant skin lesions. The accumulation of Type 2 chain H-antigen in oral premalignant lesions and the loss of the same antigen in skin premalignant lesions may prove helpful in early diagnosis of epithelial malignancy.