Age-associated increase in CD28- T-cells have been observed including a decrease in thymic output, a decrease in diversity and an increase in the number of memory and effector/memory cells. Investigators are working to develop methods to sustain or activate CD28 expression in T-cells.

Telomere is a specialized structure at the end of a chromosome involved in cellular replication and stability that erodes with aging.

"Cells, including lymphocytes, with significantly shortened telomeres are incapable of undergoing further cell division. It has been shown that the telomere lengths of blood lymphocytes are often shorter in old than in young adults. The significance of such changes in the elderly is currently under intensive studies." Dr. Weng said. The future direction is to "understand the role of telomere and telomerase in lymphocyte function in vivo with aging, and develop strategies to maintain telomere length or even lengthen telomere under certain circumstances."

Source: American College of Allergy, Asthma and Immunology