Telomerase activity in peripheral blood mononuclear cells of systemic connective tissue diseases.

OBJECTIVE: Telomerase activity has been detected in a large number of cancers, as well as human germline tissue, but is absent in most normal somatic tissue. It has been reported that telomerase is also expressed at a low level in normal peripheral blood lymphocytes and that its activity is increased by antigen processing. We investigated if the telomerase activity in peripheral blood mononuclear cells (PBMC) from patients with systemic connective tissue diseases reflects disease activity. METHODS: We examined the enzyme activity of PBMC from patients with systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), primary Sjogren's syndrome (SS), and systemic sclerosis (SSc) using the telomeric repeat amplification protocol. In SLE and SS patients, the telomerase activity level was assessed for correlations with clinical disease activity. RESULTS: Telomerase activity was detected in 64.7% (11/17) of SLE patients, 63.6% (7/11) of MCTD, 54.5% (6/11) of SS, and 44.4% (4/9) of SSc. There was a significant correlation between SLE Disease Activity Index scores and telomerase activity in patients with SLE (p < 0.01). In patients with SS, telomerase activity was detected predominantly in patients with extraglandular manifestations, but was less detectable in patients without extraglandular manifestations (p < 0.05). CONCLUSION: Our data show that telomerase activity of PBMC is an indicator of disease activity, and may play a role in pathogenesis of systemic connective tissue diseases.