CD45RB expression refines delineation of memory CD4 T cells and aids in understanding their development (91.8)

Abstract

Abstract Upon immunization, CD4 T cell stimulation leads to the development of effectors cells and of 2 major subsets of memory cells: central and effector memory cells, the latter often defined by their differential expression of CD62L and CD44. It is still unclear whether central memory cells derive from effectors or are directly induced. Our results have shown that CD44hi cells can be divided into 2 different subtypes depending on their expression level of CD45RB, providing a precise distinction among central and effector memory CD4 T cells. Using these markers, we show that while central memory CD4 T cells are absent in young mice, they are enriched in old and thymectomized animals To understand the properties of the subsets defined by CD45RB and the establishment of the central and effector memory pools, we followed the fate of transferred naïve 5C.C7 T cell receptor transgenic cells, specific for pigeon cytochrome. During the first days following immunization, virtually all the transferred cells adopt the phenotype associated with effector or effector memory cells. After a month, essentially all 5C.C7 cells in lymphoid organs express phenotypes associated with central memory cells, while in the lung effector T cells are still found. Analysis of the mean “life” of these memory cells and their cycling within the lymphoid and the non-lymphoid organs is under investigation. Taken together, these observations suggest that CD45RB, together with CD44 and CD62L, provides a powerful tool to identify and quantitate naïve, effector and memory cells in lymphoid and non-lymphoid organs. This work was supported by the Intramural Research Program of the NIAID.