ABNORMAL EXPRESSION OF APOPTOSIS-RELATED ANTIGENS, FAS AND BCL-2, ON CIRCULATING T-LYMPHOCYTE SUBSETS IN PRIMARY SJOGRENS-SYNDROME

Objective. To clarify the pathological role of the apoptosis-related m olecules expressed on peripheral blood (PB) lymphocyte subsets in prim ary Sjogren's syndrome (SS). Methods. The levels of apoptosis-regulati ng proteins, Fas and bcl-2, were determined in the PB lymphocyte subse ts from 21 patients with SS and 14 healthy controls by 2-color flow cy tometry. Results. In the PB from SS patients, lymphocytopenia, especia lly CD4+ cell-lymphocytopenia, was prominent. As observed in previous studies, the percentages of CD4+ CD45RA + cells were lower in the SS p atients than in the controls, while activated (DR+) cells were increas ed in CD4+ cells from the patients. Fas+ cells were also increased in the patients' CD4+ cells and CD8+ cells, but not in their B cells or n atural killer cells. Furthermore, we observed several positive correla tions among the percentages of activated cells (DR+ cells or CD45RA- c ells) and Fas+ cells recognized in the CD4+ and/or CD8+ cells from the patients. On the other hand, intra-cellular bcl-2 proteins measured a s mean fluorescence intensity were significantly diminished in the CD4 + cells, CD8+ cells, CD19+ cells, CD45RO+ cells and Fas+ cells from 14 SS patients compared with 12 healthy controls. In addition, the numbe rs and/or percentages of CD4+ cells and Fas+ cells positively correlat ed with their expression of bcl-2 in SS patients. Conclusion. The abno rmal balance between Fas and bcl-2 expression detected in the PB lymph ocyte subsets from SS patients relates, at least partially, to the lym phocytapenia observed in the patients.