LAUSR

Long-term T cell memory is dependent on the maintenance of memory T cells in the lymphoid tissues, and at the surface interfaces which provide entry routes for pathogens. However, much of the current information on human T cell memory is based on analyzing circulating T cells. Here, we have studied the distribution and age-related changes of memory T cell subsets in samples from blood, mesenteric lymph nodes, spleen, and ileum, obtained from donors ranging in age from 5 days to 67 years of age. Our data show that the main reservoir of polyclonal naive cells is found in the lymph nodes, and the resting memory subsets capable of self-renewal are also prominent there. In contrast, non-dividing but functionally active memory subsets dominate the spleen, and especially the ileum. In general, the replacement of naive cells with memory subsets continues throughout our period of observation, with no apparent plateau. In conclusion, the analysis of lymphoid and nonlymphoid tissues reveals a dynamic pattern of changes distinct to each tissue, and with substantial differences between CD4+ and CD8+ compartments. This article is protected by copyright. All rights reserved.