Donor CD8⁺ T-cell expansion is impaired in asmase^−/− hosts. C57BL/6^asmase+/+ and C57BL/6^{asmase−/−} recipients were infused with 15 to 20⁶ CFSE-stained splenic CD3⁺ T cells from LP/J donors as described in “Flow cytometric analysis and in vivo CFSE staining.” Spleens were harvested 7 days thereafter and multicolor flow cytometry was performed. Percentage of CFSE “high” (cells with mean fluorescent values ≥ 10⁴) and “low” (mean fluorescent values ≤ 10³) CD4⁺ and CD8⁺ populations are shown from 1 representative of 2 independent experiments.