Differential contributions of central and effector memory T cells to recall responses

Although the absolute number of memory CD8+ T cells established in the spleen following antigen encounter remains stable for many years, the relative capacity of these cells to mediate recall responses is not known. Here we used a dual adoptive transfer approach to demonstrate a progressive increase in the quality of memory T cell pools in terms of their ability to proliferate and accumulate at effector sites in response to secondary pathogen challenge. This temporal increase in efficacy occurred in CD62L lo (effector memory) and CD62L hi (central memory) subpopulations, but was most prominent in the CD62L hi subpopulation. These data indicate that the contribution of effector memory and central memory T cells to the recall response changes substantially over time.