Maintenance of antigen-specific memory cells is not dependent on SLP-76. cHET and cKO mice were bled longitudinally, and peripheral blood lymphocytes were isolated and stained for multicolor flow cytometry. (A) SLP-76–deficient CD44^hi cell number was determined longitudinally in peripheral blood samples (left) and spleens (right). (B) Total GP33-specific CD8⁺ T cells enumerated from peripheral blood (left) and spleen (right). (C) YFP⁺H-2D^b:GP33-specific CD8⁺ T cells enumerated from peripheral blood (left) and from spleen (right). For the longitudinal studies, cells were gated on populations as indicated, and normalized to number of cells per 1 million lymphocytes, as described in “Quantification of T lymphocytes from peripheral blood.” Data points are shown as mean and standard deviations. Black represents cHET; and gray, cKO. Longitudinal bleeding data are compiled from 15 mice in 2 independent infections. Splenocyte numbers are compiled from mice at 6, 10, and 48 weeks after infection in a total of 4 independent infections.