Observations on the in vivo reaction of antinuclear antibodies with epidermal cells

In evaluating the normal skin of five patients with mixed connective tissue disease, four patients were noted to have both basement membrane zone and speckled epidermal nuclear immunofluorescence. The positive epidermal nuclear reaction was found to be associated with IgG, and no evidence of complement involvement was seen. In vitro testing demonstrated that normal control skin incubated with high-titred antisera to nuclear ribonucleoprotein reporduced the findings observed in direct staining, but incubation with high-titred antisera to other nuclear antigens such as Sm and single-stranded deoxyribonucleic acid did not cause positive epidermal nuclear staining. The association of antibodies to ribonucleoprotein and speckled epidermal nuclear immunofluorescence is discussed. Also considered is the possibility of other factors affecting nuclear membrane permeability.