Expression of Ro/SS-A antigen in human skin and heart.

Using human sera monospecific for anti-Ro/SS-A antibodies in an indirect immunofluorescence assay, Ro/SS-A antigen was found to be present in nuclei of human fetal ectodermal cells and newborn epidermal keratinocytes, but not in adult epidermal keratinocytes. After in vitro cultivation, Ro/SS-A antigen was also found in the nuclei of adult skin explant outgrowth cells. The localization of Ro/SS-A in fetal heart could not be precisely determined (possibly nuclear and membrane). Extracts from fetal skin and heart contained Ro/SS-A antigen which is identical to the Ro/SS-A present in WiL2 cell extract. The molecular weight of Ro/SS-A antigenic peptide present in these extracts is around 60K.