Effects of pemphigus antibody on the regeneration of cell-cell contact in keratinocyte cultures grown in low to normal Ca++ concentration.

Pemphigus is an autoimmune blistering disease of epidermal cells in which autoantibodies to the surface develop. The present study was performed to determine whether the binding of pemphigus antibodies to the surface of keratinocytes can inhibit the regeneration of cell-cell contact induced by altering from low to normal Ca++ concentration medium. Human keratinocytes (a cell line of squamous cell carcinoma, DJM-1 cell) were grown in low Ca++ medium for 4 days, then the cells were incubated in normal Ca++ medium containing 10% pemphigus (4 patients with pemphigus vulgaris and 4 patients with pemphigus foliaceus) or normal serum (treated at 56 degrees C, for 30 min) for various incubation periods (2, 6, 12, 24 h). The cells were fixed and stained with antikeratin antibody by the indirect immunofluorescence method so that the detachment of cell-cell contact was able to be clearly visualized by observing the cytoskeletal arrays of keratin filaments. The cells grown in normal Ca++ medium showed detachments of cell-cell contact 24-36 h after addition of any one of the pemphigus sera used in this study. The cells grown in low Ca++ medium formed no cell-cell contacts and expressed no pemphigus antigens. However, re-formation of cell-cell contacts and reexpression of the antigens were confirmed by immunofluorescence microscopy 30 min after the addition of Ca++ to the medium. The addition of any pemphigus vulgaris and foliaceus sera with Ca++ did not inhibit the regeneration of cell-cell contact and exerted no effects on the contact during the subsequent 12 h. However, after 24 h, these cells again lost the contact. These results indicate that pemphigus antibody and antigen reaction on the cell surface did not directly inhibit the Ca++-induced re-formation of cell-cell contact.