Human immunodeficiency virus type 1 modulates telomerase activity in peripheral blood lymphocytes

The effect of human immunodeficiency virus type 1 (HIV-1) on telomerase activity in peripheral blood lymphocytes (PBL) was examined. Telomerase is an enzyme that is involved in mechanisms that control cell life span and replicative potential. HIV-1 reduced telomerase activity in in vitro-infected PBL and impaired enzyme activation upon cell stimulation. Telomerase activity was significantly lower in PBL from 23 HIV-1-infected patients than in PBL from healthy donors and significantly increased during highly active antiretroviral therapy (HAART) in 10 patients who had both a virological and an immunological response and in 5 and 8 patients with a virological or an immunological response, respectively. Further analyses of fractionated cells revealed that telomerase activity increased mainly in CD4⁺ lymphocytes. Overall, these findings demonstrate that HIV-1 infection down-modulates telomerase activity and suggest that both the HIV-1 decline and immunorestoration in response to HAART contribute to increased telomerase activity in CD4⁺ lymphocytes.