Immunohistochemistry to detect p53 and its transcription target p21, which is expressed only if p53 is functional and not mutated, was performed on labial salivary glands (LSG) from 10 patients with primary SS, all of whom had a Chisholm grade 4 LSG biopsy, and from 10 control patients with sicca symptoms or systemic diseases and a normal LSG biopsy (grade 0 or 1).