In vitro binding of IgG from patients with primary and secondary Sjögren's syndrome to different components of keratinized stratified squamous epithelia.

The ability of serum IgG from patients with Sjögren's syndrome (SS) to bind to keratinized stratified squamous epithelium of human skin or rat oesophagus was examined, using an indirect immunofluorescence technique. No in vitro binding of serum IgG to the cell membranes of normal human epidermis was demonstrated in 7 patients with primary SS and two normal controls. Thus, the intraepidermal in vivo IgG deposits previously found in 5 of the 7 patients could not be imitated in vitro. Examination for in vitro binding to rat oesophageal epithelium of serum IgG from 21 consecutive patients with primary SS, 19 consecutive patients with rheumatoid arthritis and secondary SS and 22 normal controls showed that antikeratin antibodies occur more frequently (p less than 0.001) in the patients with secondary SS compared to patients with primary SS and to normal controls.