Pemphigus, pemphigoid, and epidermal upper-cytoplasmic antigens: changes in expression in cultured human keratinocytes.

In an approach of epidermal differentiation, the expression of pemphigus, bullous pemphigoid, and upper-cytoplasmic epidermal antigens was studied in human keratinocytes in culture. The cells were cultured without feeder cells, dermal tissue, or collagen at an acid pH (5.6--5.8) similar to that of the surface of the skin in vivo. Cell suspensions from fresh trypsinized skin and primary, secondary, and tertiary cultures were tested by indirect immunofluorescence for the presence of each antigen using human sera from patients with pemphigus, bullous pemphigoid, and human sera with antibodies against upper-cytoplasmic antigens. Normal sera and cultured human normal fibroblasts and melanoma cells were used as controls. Pemphigus and pemphigoid antigens were found to be expressed, and synthesized by keratinocytes in vitro. The expression to upper-cytoplasmic antigens decreased with time in culture, and they were absent in secondary or tertiary cultures, while expressed by 45--65% of cells prepared from fresh skin. Both upper-cytoplasmic and pemphigoid antigens can be used to type subpopulations of human epidermal cells; however, these findings suggest that epidermal differentiation in vitro differs from that which occurs in vivo.