Table I.

Telomerase activity in autoimmune diseases.

No.	Disease	Telomerase activity in autoimmune disease	(Refs.)
1	Rheumatoid arthritis	The telomerase activity level in synovial infiltrating lymphocytes was significantly correlated with the intensity of synovial lining hyperplasia, microvessel proliferation, lymphocyte infiltration, and percentage of synovial cells positive for proliferating cell nuclear antigen in rheumatoid synovium	Yudoh et al (26)
		Activated lymphocytes with high telomerase activity distribute systemically through the circulation and contribute disease activity in connective tissue disease. The stimulatory effect of estrogens on telomerase activity and female predominance in connective tissue disease may contribute to high telomerase activity in these pathologies.	Hiyama and Hiyama (27); Yamanishi et al (187); Tarhan et al (188)
		Telomerase activity in lymphoid cells of lymphoid organs is higher than in peripheral blood.	Hiyama and Hiyama (27);
		Highest hTERT values were observed in Rheumatoid arthritis group (21.24±28.54). hTERT values were significantly higher than the healthy control group (7.62±4.21) (P<0.05).	Tarhan et al (188); Yudoh et al (26)
		Lack of telomerase activity leads to excessive loss of T cells, which limits the possibility of homeostatic control of naive T-lymphocytes.	Fujii et al (28)
		T cells as a result of repeated stimulations correspond to decreasing peaks of mRNA and hTERT induction, compared with the first highest peak.	Valensuela and Effros (141)
2	Systemic lupus erythematosus	High telomerase activity in peripheral blood mononuclear cells.	Katayama and Kohriyama (29)
		Significant correlation between telomerase activity and disease severity. With an exacerbation of the disease, telomerase activity in mononuclear cells of peripheral blood is significantly higher than in the control group.	Klapper et al (43); Kurosaka et al (189)
		There was no evidence of telomere shortening in lymphocytes and no correlation between telomerase activity and telomere length.	Klapper et al (43); Kurosaka et al (189)
		The activity of telomerase in the cells is sufficient to compensate for the shortening of telomeres, and thus prevent the accelerated aging of the immune system of patients.	Klapper et al (43)
3	Systemic sclerosis	The most interesting finding was very low PBC hTERT levels in the Systemic sclerosis group. If really there is a tendency for lower telomerase activity in Systemic sclerosis, this may be related with the telomere shortening reported by Artlett et al. The authors hypothesized that the chromosomal instability observed in Systemic sclerosis patients may result from the loss of long stretches of the telomeric repeats. Telomeric shortening may be expected to stimulate telomerase activation; however, the reverse may also be true. In other words, since the expression of telomerase stabilizes telomere length and allows for continual replication, low telomerase activity may contribute to telomere shortening.	Tarhan et al (188); Artlett et al (58)
		T lymphocyte homeostasis is significantly impaired.	Hug et al (190); Tarhan et al (188); Katayama and Kohriyama (29)
		Thymic T cell production was estimated by measuring TCR excision circles (TRECs) as a traceable molecular marker in recent thymic emigrants. an impaired thymic export function and, as a consequence, altered ability to maintain T cell homeostasis and immune tolerance may play an important pathogenic role in relapsing remitting Multiplex Sclerosis.	Hug et al (190)
		T cells as a result of repeated stimulations correspond to decreasing peaks of mRNA and hTERT induction, compared with the first highest peak.	Valensuela and Effros (141)
4	Atopic dermatitis and psoriasis	Telomerase activity in the affected areas of the skin is significantly higher than in intact skin and is associated with proliferative activity of the cell.	Jang et al (191)
		Lymphocytes that infiltrate the epidermis are not responsible for the level of telomerase, since it does not correlate with the number of these lymphocytes.	Ogoshi et al (192); Taylor et al (193)
		The level of telomerase activity in skin diseases that are not malignant is much lower than in malignant tumors.	Taylor et al (193)
		A high level of telomerase activity in peripheral blood mononuclear cells compared to donors.	Wu et al (46)
5		The length of telomeres in blood cells progressively decreases by 216 base pairs in addition to the age loss of 36 base pairs per year.	Brümmendorf et al (194); Fogarty et al (195)
		The telomere reduction and short cell life can be explained by the presence of mutations associated with this disease in the hTR and hTERT genes.	Ly (196); Young (197); Yamaguchi et al (198); Marrone et al (199)
		Most patients carrying these mutations are insensitive to immunosuppressive therapy.	Ly (196); Young (197); Yamaguchi et al (198); Marrone et al (199)
		Among patients with polymorphisms in the TERT gene, the telomere length was within 90% of the values of healthy donors.	Yamaguchi et al (198)