The cytoskeleton and extracellular matrix of the Dupuytren's disease "myofibroblast": an immunofluorescence study of a nonmuscle cell type.

The cytoskeleton and the extracellular matrix of myofibroblasts in nodules from Dupuytren's diseased palmar fascia were examined by indirect immunofluorescence. Primary antibodies used as probes of these tissue compartments were directed against (1) smooth muscle myosin, (2) nonmuscle myosin--components of the cytoplasmic contractile apparatus in smooth muscle and nonmuscle cells, respectively, (3) laminin, and (4) fibronectin--extracellular glycoproteins mediating cell-matrix attachment in smooth muscle and nonmuscle fibroblastic cells, respectively. The Dupuytren's nodular cells stained for nonmuscle myosin and fibronectin but not for smooth muscle myosin or laminin; this indicated that, at the level of biochemical differentiation, these cells are a nonmuscle type. Staining for fibronectin between nodular cells was dramatically increased over that seen between fibroblasts of the normal palmar fascia. Because of the non-muscle nature of the distinctive contractile cell type of the Dupuytren's nodule, we suggest that the term myofibroblast should be considered a misnomer when applied to this pathogenic cell type.