THE GROWTH AND DIFFERENTIATION OF HUMAN KERATINOCYTES IN-VITRO - A COMBINED IMMUNOHISTOCHEMICAL AND FLOW CYTOMETRIC STUDY

In this study we performed a cell kinetic characterization of the grow th and differentiation of human keratinocytes. Using a combination of immunohistochemical and flow cytometric techniques it was possible to obtain a detailed description of these processes. The proliferative ac tivity of the cell cultures was analysed with flow cytometric techniqu es, measuring relative DNA content, iododeoxyuridine incorporation and the expression of the antigen recognized by Ki-67. In addition to a s tandard monolayer culture technique, cells were maintained in suspensi on. Under these conditions these cells were not capable of dividing, s tarted to lose their nuclei, and the expression of differentiation-rel ated proteins such as involucrin and filaggrin was induced, suggesting that the cells changed towards a differentiated phenotype. Binding of the antibody K(s)8.12, recognizing keratins 13 and 16, occurred under all culture conditions, independent of cell density, and also in susp ension, suggesting that it is a marker for abnormal differentiation ra ther than for hyperproliferation.