Figure 7.
Conversion of CD44 to its active form occurs on Treg cells in vivo and is associated with increased suppressor function. (A) C57Bl/6-Thy1.1 congenic hosts were injected intravenously with 20 × 106 freshly isolated Balb/c CD4CD25+ T cells (Thy1.2). After 72 hours, spleen cells were stained with Thy1.2-allophycocyanin, CD44-PE, and Fl-HA. Fl-HA/CD44 staining of cells gated on Thy1.2 is shown with and without KM81 blocking. (B) CD44act– and CD44act+ fractions in the Thy1.2 gate were sorted as shown and placed in an in vitro anti-CD3 suppressor assay with 2.5 × 104 CD4CD25– responders. Suppressor activity (mean ± SEM for 2 experiments) is significantly enhanced in the in vivo arising CD44act+ population. *Statistical comparison of CD44act+ to CD44act– and to unactivated Treg cell groups. P ≤ .001 for both pairwise comparisons.