The demonstration of SS-A/Ro antigen in human fetal tissues and in neonatal and adult skin.

Anti-SS-A/Ro antibodies have been statistically associated with congenital heart block and cutaneous lupus in the neonatal lupus syndrome, and with photosensitive cutaneous lupus in subacute cutaneous lupus erythematosus, but it had not been demonstrated that SS-A/Ro antigen is present in fetal tissues or at any age in human skin. We examined normal fetal tissues, normal neonatal and adult skin, and keratinocytes from purified serum-free cultures by immunofluorescence (IF) and by immunodiffusion or counterimmunoelectrophoresis (CIE) to determine the presence of SS-A/Ro antigen. We found SS-A/Ro antigen to be present in fetal hearts and in other internal organs. SS-A/Ro antigen could be demonstrated in biopsies of neonatal and adult skin by IF and was confirmed to be in keratinocytes by CIE. SS-A/Ro antigen may be found on the surface of keratinocytes in culture and therefore may be present at a relevant site for antibody binding. We have shown that SS-A/Ro antigen is a normal component of tissues that may be affected in neonatal lupus (fetal myocardium, neonatal epidermis) and in subacute cutaneous lupus erythematosus (adult epidermis).