Phenotypic and functional abnormalities in the peripheral blood T-cells of patients with primary Sjogren's syndrome.

Changes in regulatory T-cell subset (including the recently described CD4 helper inducers or suppressor inducers) balance in the peripheral blood may play a role in the pathogenesis of primary Sjogren's syndrome (SS). Direct immunofluorescence and flow cytometry were used to quantitate and analyse peripheral blood lymphocytes in 15 patients with primary SS and 15 control subjects. A reduction in the percentage of circulating CD4 lymphocytes was observed in patients with SS. There was no quantitative abnormality in the percentage of circulating CD4+ 2H4+ (suppressor inducer), CD4+ 4B4+ (helper inducer), CD2, CD3, CD8, CD8+ 2H4+, CD8+ 4B4+, CD25 (IL-2R), CD19, CD16, CD57 lymphocytes in the patients. Circulating CD8 lymphocytes expressing the activation marker HLA-DR were increased in the patients. The functional status of peripheral blood lymphocytes was assessed by PHA (phytohaemagglutinin) stimulation followed by monitoring their proliferative response by radiolabelled thymidine uptake and expression of CD25 (Interleukin-2 receptor). A reduction in the proliferative response of total, CD4-depleted, and CD8-depleted lymphocytes suspensions to PHA was demonstrated. The level of expression of CD25 (IL-2 receptor) was similar in patients and controls before and after 24 h stimulation with PHA. We conclude that there is a disturbance in the functional properties of peripheral blood T cells that can contribute to the immunopathogenesis of SS. Meanwhile, the quantitative reduction of suppressor/inducer lymphocytes as defined by the CD4 2H4 phenotype can be precluded from a role in the development of such an autoimmune condition.