Primary Sjögren's syndrome (1 degree SS) is an autoimmune disease, usually accompanied by manifest immune hyperactivity. In some cases the disease converts to malignant neoplasia. On the other hand, there are clinical similarities to HIV infection. Since the rare phenomenon of persistent depletion of CD4+ T-lymphocytes in peripheral blood without HIV infection was recently defined as idiopathic CD4+ T-lymphocytopenia (ICL), we have used the ICL criteria to investigate the prevalence of this phenomenon among 1 degree SS patients.
During the period 1988-94, 115 caucasian patients (10 males), mean age 57.8 (range 19-82) years, with 1 degree SS were prospectively studied. Lymphocyte subsets were investigated by means of monoclonal antibodies and flow cytometry. For the detection of HIV and HTLV antibodies, we used an enzyme immunoassay (for HIV-1 and HIV-2), Western blot techniques (HIV-1, HIV-2, HTLV-I and HTLV-II), and the polymerase chain reaction procedure (HIV-1, HTLV-I and HTLV-II). HIV antigens were tested for with the HIV-1 p-24 Ag test.
Six patients with 1 degree SS fulfilled the criteria for ICL. While the clinical condition of 5 of those six patients remained stable, one patient developed malignant lymphoma three years after her disease was classified as a case of ICL. The prevalence of ICL among our 115 patients with 1 degree SS was 5.2%, which is significantly higher than the rates reported for any other patient or population group. We have estimated the relative risk of ICL in 1 degree SS patients to vary from 3.4 to 6,000 (P values of 0.0001-0.025).
We suggest that subjects with ICL should be carefully examined for 1 degree SS and, if its presence is confirmed, that they should be followed with regard to the possible complications of this disease, including the development of malignant lymphoma.