OX40 signaling sustains A1 expression and survival in CD8 T cells.

(a) Naive CD8 T cells from WT OT-I TCR transgenic mice were stimulated in vitro with T-depleted APCs and OVA peptide in the presence or absence of 10 µg/ml agonist anti-OX40 or rat IgG added on day 0 and day 2. (b) After 5 days of primary culture, live T cells were isolated and restimulated with T-depleted APCs and OVA peptide in the presence or absence of 10 µg/ml agonist anti-OX40 or rat IgG added. Data show the percentage T cell recovery, calculated based on assigning the input number of cells in each culture as 100%. Data are mean ± s.d from three experiments (p>0.05). Cell lysates were analyzed by immunoblotting for A1 and β-actin (top). Protein amounts were determined by densitometry and are shown relative to the expression in wild-type T cells treated with rat IgG on day 4 or 2 (taken as 1).