Telomerase activity might persist in the human thymus throughout life.

Telomerase activity has been demonstrated at low levels in peripheral blood lymphocytes but at high levels in germinal centre B cells and thymocyte subpopulations. This study shows that telomerase is activated in the normal human thymus at different times of life. Telomerase activity was detected in thymic protein extracts from two newborn babies and from a 12 year old boy, as well as in extracts from two of six adult patients. The two positive cases were patients aged 54 and 66 years. These results suggest strongly that the thymus can remain functional despite involution in elderly patients.