. Sjogren's syndrome is an autoimmune disease characterized by lacrimal gland (LG) B-cell proliferation, dysfunction and ultimate destruction of LG secretory epithelium resulting in decreased aqueous tear production. Severe ocular surface alterations including squamous metaplasia, goblet cell loss and lymphocytic infiltration are detected in the majority of SS patients. The mechanism(s) responsible for the pathological processes manifested In SS are not well-understood. Specific attention has been given to Epstein-Barr virus (EBV), a ubiquitous human herpes virus that has been shown to be the etiologic agent for several ocular diseases. EBV has been implicated in the pathogenesis of SS for several reasons, among which are that: serologic evidence of chronic EBV infection is found in SS patients, it can infect B-cells and it is a potent polyclonal B-cell activator, and the LG lymphoid infiltrate in SS consists predominantly of B-cells; EBV positive lymphoblastoid B-cell lines that grow spontaneously in vitro can be obtained readily from patients with SS; EBV genomic sequences have been detected in salivary and LC, DNA, PBMN DNA and tear specimens of patients with SS at a significantly higher frequency than in specimens from normal patients. B-cells are thought to harbor latent EBV genomes without viral replication whereas epithelial cells allow for productive EBV infection. Both B-cells and epithelial cells are found within the normal LG. If EBV plays a role in the pathogenesis of SS, then it should be possible to determine which of the cell types within the LG and ocular surface mucosa harbor EBV, and if the EBV genomic sequences detected in SS LG tissue are from latent or productive virus.
The aims of the research proposed herein are to: (1) identify the cell types permissive for EBV in the normal LG and determine if EBV is latent or lytic within the LG; (2) identify the cellular location and lifecycle status of EBV in the LG and ocular surface mucosa of SS patients, and (3) determine if the lymphoproliferation in SS LGs are the result of EBV transformed B-cells. The goals of this project will be achieved by: (1) immunohistochemical techniques using monoclonal antibodies specific for EBV antigens and cellular surface membrane epitopes to locate EBV within normal and SS LG tissue. (2) In situ DNA:RNA hybridizations to determine the location of EBV productive and/or latent transcripts within the normal and SS LG tissues. (3) Establishment of lymphoblastoid cell lines to identify EBV transformed B-cells within SS LGs.
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