Decreased CD161+CD8+ T cells in the peripheral blood of patients suffering from rheumatic diseases

Abstract

Objectives. Although it has been reported that the numbers of both CD4-CD8- and CD4+ natural killer T (NKT) cells are selectively decreased in the peripheral blood of patients with rheumatic diseases, there have been no reports concerning a novel subpopulation of CD8+ NKT cells. To examine whether CD161+ CD8+ T cells, which are closely related to CD8+ NKT cells, are also decreased in patients with rheumatic diseases, we have investigated the expression of CD161, together with that of CD28, CD25 and CD62L, on T cells in the peripheral blood of these patients. Methods. The rheumatic diseases evaluated in this study were systemic lupus erythematosus (SLE) (n = 54), mixed connective-tissue disease (MCTD) (n = 15), systemic sclerosis (SSc) (n = 14), polymyositis/ dermatomyositis (PM/DM) (n = 13) and rheumatoid arthritis (RA) (n = 24). Healthy donors were examined as controls (n = 18). The expression of CD161, CD28, CD25 and CD62L on T cells was analysed by flow cytometry. Results. Both the frequency of CD161 expression on CD8+ cells and the absolute number of CD161+ CD8+ cells were significantly decreased in patients with SLE, MCTD, SSc and PM/DM. Only the absolute number of CD161+ CD8+ T cells was significantly decreased in RA. CD161 expression on CD28- CD8+ T cells was significantly decreased in SLE, MCTD and SSc. The absolute number of CD161+ CD8+ CD62L- T cells was significantly decreased in SLE, MCTD and SSc. Conclusions. Both the frequency and the absolute number of CD161+ CD8+ T cells were decreased in the peripheral blood of patients suffering from SLE, MCTD, SSc and PM/DM. This result suggests that there is also an abnormality of NKT cells in the CD8+ population. © 2006 Oxford University Press.