Binding of antibodies to nonhistone nucleoproteins on keratinocytes in suspensions

Antibody binding on the cell surface of epidermal cells, recently established on cultured neonatal foreskin cells, is supposed to play a role in the pathogenesis of in vivo antinuclear antibodies (ANA) of the skin. To study this phenomenon in suspensions of adult human keratinocytes, a cell system more closely related to the in vivo situation, we investigated the binding capacity of nine sera with various antibody profiles against nuclear components, as well as a murine monoclonal Sm-antibody. It was found that sera containing antibodies against nonhistone nucleoproteins bound to the cell surface of keratinocytes, whereas monospecific anti-dsDNA sera and the murine anti-Sm serum did not. This binding was found in both basal and suprabasal keratinocytes. The percentage of cells showing antibody binding was not significantly enhanced by preirradiation with ultraviolet light, as was found in a previously study. The cell surface binding is probably an antigen-antibody binding and not the result of cross-reactivity. Such cell surface binding may be important for the formation of in vivo ANA in the skin.