CD3^-CD5⁺ cells express markers characteristic of memory CTLs. Fresh, unstimulated splenocytes from mice were stained with antibodies to CD3, CD5, and one of the following activation/memory markers: CD44, Ly-6C, CD25 (IL-2Rα), and CD122 (IL-2Rβ) and evaluated by flow cytometry. Strains and cell populations gated are listed to the left of the indicated row. The percentage of viable gated cells expressing each activation/memory marker is indicated. The D^d-ζ cells were obtained from homozygous 130 strain mice.