Detection of the tax gene of HTLV-I in labial salivary glands from patients with Sjogren's syndrome and other diseases of the oral cavity

Objective To confirm a possible association between Sjogren's syndrome (SS) and the t ax gene of human T lymphotropic virus type I(HTLV-I). Methods We studied by PCR labial salivary glands (LSG) from 50 patients with defini te SS and from 58 controls including 32 patients with LSG involved by other inflammatory processes and 26 normal LSG. Antibodies to HTLV-I and antibod ies to the Tax protein were searched for in serum. Results We detected the tax gene of HTLV-I in LSG from 15/50 (30%) of patients with SS but also in specimens from 9/32 (28%) patients with LSG involved by oth er inflammatory processes (3/9 graft-versus-host disease, 5/19 extravasated cysts, 1/4 sarcoidosis) and from only 1/26 (4%) normal LSG. A 652 bp regio n, sequenced in 2 SS patients, was 98 - 98.5% homologous to the canonic seq uence of tax HTLV-I. The HTLV-I gag, pol and env genes were never detected The serum of the SS patients did not contain antibodies to HTLV-I. However anti-Tax antibodies were detected in the serum of 18/25 (72%) SS patients, 10/10 (100%) patients positive for tax DNA in their LSG and 8/15 (53%) pati ents negative for tax DNA in their LSG. Conclusion Our observations raise the possibility that a very low number of copies of the tax gene may be harbored innocuously in cells within the oral cavity in some healthy individuals, but that this gene may play a role as a co-facto r in the development of SS or other diseases of oral cavity.