Double-negative (CD4-CD8-) TCRalphabeta+ cells in patients with systemic lupus erythematosus

Massive accumulation of CD4-CD8-TCRalphabeta+ cells in secondary lymphoid organs is characteristic of lupus-prone MRL/lpr mice. However, the role of these double negative T cells (DNT) in human lupus patients receive only limited attention. Herein, we investigate the frequency of DNT in the peripheral blood mononuclear cells of forty seven Chinese patients with systemic lupus erythematosus (SLE) and forty four normal individuals. DNT were measured with dual-fluorescence flow cytometry. The results showed that DNT only constituted a very minor subset of lymphocytes both in patients and normals, it normally did not exceed 2% of the lymphocyte population. Compared with normal subjects, patients with SLE had slightly increased levels of DNT within the total lymphocyte population (0.66+/-0.45% vs 0.51+/-0.33%) or within TCRalphabeta+ population (1.14+/-0.88% vs 0.88+/-0.54%). The difference, however, did not reach statistical significance. The levels of DNT correlated neither with the titers of anti-DNA antibodies in sera nor with the presence of active and severe lupus nephritis in SLE patients. Longitudinal follow-up of six patients at the stages of active and inactive nephritis revealed similar levels of DNT in the same individual. The preliminary results suggest that circulating DNT do not appear to play a critical role in Chinese patients with SLE.