Sjogren's syndrome (SS) is an autoimmune disease that primarily affects the salivary and lacrimal glands. These structures become extensively infiltrated with lymphocytes and plasma cells. Glandular architecture is disrupted, resulting in diminished or lost salivation and lacrimation. In some individuals, the condition progresses systemically and may involve the development of lymphoma and generalized wasting. HIV-infected patients can also develop a glandular exocrinopathy that is symptomatically and histologically similar to SS. Because of these shared characteristics between SS and HIV-induced disease, a possible virus associated with primary SS was sought A significant percentage of serum samples obtained from patients having primary Sjogren's disease were found to have detectable levels of antibody to the major capsid protein antigen of HIV-1, p24. Some of the sera also recognized a second HIV-1 capsid protein antigen, p17 Cocultures of salivary gland biopsy material from patients having SS with a human lymphoblastoid cell line (H9) produced cultures positive for the production of HIV-1 p24-related antigen. This antigen was found to be associated with the retroviral enzyme reverse transcriptase. Electron micrographic studies of these cultures revealed the presence of intracellular A-type retroviruses. This novel human virus was designated the 'human intracisternal A-type particle' (HIAP) During the course of the characterization of the HIAP reverse transcriptase, a cellular enzyme having reverse transcriptase activity was found. It differed from the HIAP enzyme in several biochemical characteristics. This H9 enzyme was also distinguishable from the known eucaryotic DNA polymerases $\alpha,\ \beta,\ \gamma,$ and $\varepsilon.$ The H9 enzyme was found to readily incorporate the triphosphorylated form of azidothymidine (AZT) into nascent DNA molecules, but it was not affected by an allosteric modulator of HIV reverse transcriptase, BI-RG-587 An additional H9 cellular component obtained through gel filtration chromatography was capable of attenuating not only the reverse transcriptase reaction of the H9 enzyme, but also those of HIAP and HIV. Another factor obtained from RT-negative HIV-infected H9 cell culture supernatants similarly reduced or abrogated various reverse transcriptase reactions. However, this inhibition appeared to take place via a different mechanism from that of the H9 cellular inhibitor