Induction by transforming growth factor β of Pemphigus vulgaris antigen activity in mouse papilloma cells

Induction of a marker of epidermal spinous cells, pemphigus antigen activity, was detected by indirect immunofluorescence in murine papilloma cells exposed to human transforming growth factor beta (TGF-beta). Detection of pemphigus antigen activity required exposure of cells to 1.4 mM Ca2+ for 3 h just prior to immunoassay. The brief exposure to Ca2+ may be necessary for translocation of intracellular pemphigus antigen to the cell surface, where it is accessible to antibody. Cells grown in medium containing 0.02-0.04 mM Ca2+ were shown previously to be primarily basal cells characterized by pemphigoid antigen activity. Following treatment with 0.25-25 pg/ml TGF-beta for 44 h under 0.02-0.04 mM Ca2+ conditions, 63 +/- 9% (SD) of cells were pemphigus positive. This percentage was comparable to that of positive control cultures exposed to 1.4 mM Ca2+ for 44 h (70 +/- 10%) and was up to 2-fold that of solvent control cultures. Pemphigus antigen activity was significantly induced by 0.1-25 pg/ml TGF-beta, out of a tested range of 10(-5)-10(3) pg/ml. The total number of papilloma cell colonies was unaffected by treatment with 0.1-25 pg/ml TGF-beta but was reduced greater than 90% by treatment with 10(3)-5 x 10(3) pg/ml TGF-beta. The described immunofluorescence assay for pemphigus antigen activity may be useful for preliminary evaluation of differentiation-inducing agents in anticarcinoma therapy.