SELL and lymphopenia: Indeed, the peripheral T-cell pool in non-immunized gnotobiotic animalscontains virtual memory T cells specific to the model antigen [2, 3].Under lymphopenia, the peripheral T lymphocytes undergo homeostaticproliferation and acquire the surface phenotype of memory T cells:CD44+CD62L+ (TML, “memory-like” Tcells) [4-7].