(A and B) Control (Stat3fl/fl) or Stat3−/− (Cd4 Cre; Stat3fl/fl) naive T cells were transferred into Rag2−/− mice and cell division was assessed by CFSE dilution.
(B) The absolute numbers of CD4+ TCR-β+ cells in the spleen at day 5 and 7 are shown; data are representative of two independent experiments.
(C) Control and Stat3−/− CD4+ T cells were cultured for 3 days in medium or with the indicated cytokines and the proportion of apoptotic (Annexin-V/PI positive) cells was determined by flow cytometry. Means (±SEM) of apoptotic cells from three independent experiments are shown. See also Figure S5. *p < 0.05; **p < 0.005.