Telomerase activity is increased and telomere length shortened in T cells from blood of patients with atopic dermatitis and psoriasis

We studied telomerase activity and telomere length in PBMC and purified CD4 (+) and CD8(+) T cells from blood obtained from a total of 32 patients with atopic dermatitis, 16 patients with psoriasis, and 30 normal controls, The telomerase activity was significantly increased in PBMC from the patients compared with PBMC from normal donors, This increase was most pronounced in the subpopulation of CD4(+) T cells, which were significantly above the ac tivity of the CD8(+) T cells in atopic dermatitis, psoriasis patients, and control persons. The telomere length was significantly reduced in all T cel l subsets from both atopic dermatitis and psoriasis patients compared with normal individuals. Furthermore, the telomere length was found to be signif icantly shorter in CD4(+) memory T cells compared with the CD4(+) naive T c ells, and both of the cell subsets from diseases were shown to be of signif icantly shorter telomere length than the same cell subsets from normal cont rols, No significant difference was observed between CD8(+)CD28(-) and CD8( +)CD28(+) T cell populations in both diseases. However, the telomere length of CD8(+)CD28(+) T cells from both diseases was significantly shorter than CD8(+)CD28(+) T cell subsets from normal donors. In conclusion, the increa sed telomerase activity and shortened telomere length indicates that T lymp hocytes in atopic dermatitis and psoriasis are chronically stimulated and h ave an increased cellular turnover in vivo.