Decreased expression of epidermal cytoplasmic antigens in cultured human keratinocytes

The expression of upper cytoplasmic (U-CYT) antigens which are expressed only in the superficial layers of the epidermis and are markers of epidermal cell differentiation in vivo and of basement zone (BMZ) antigens reacting with bullous pemphigoid serum was studied in keratinocytes in tissue culture. The cells were cultured at an acid pH (5.6-5.8) similar to that of skin and without feeder cells, dermal tissue, or collagen. It was found that the expression of U-CYT antigens decreased markedly in culture. These antigens were expressed in 45-65% of epidermal cells prepared from fresh skin, but in only 5-10% of cells which had been grown in primary culture over 1 mo, and in no cells in secondary or tertiary culture. By contrast, BMZ antigens continued to be expressed in culture. These antigens were expressed by 20-35% of epidermal cells prepared from fresh tissue and by 15-35% of keratinocytes in primary, secondary or tertiary culture. These findings indicate that U-CYT and BMZ antigens can be used to type subpopulations of human keratinocytes in suspension, and suggest that the differentiation of these cells in vitro differs from that which occurs in vivo.