Retroviral transduction of OX40 KO CD8 T cells with A1 reverses defective survival <i>in vitro</i>.

<p>Naive CD8 T cells from WT or OX40 KO OT-I TCR transgenic mice were stimulated with T-depleted APCs and OVA peptide, and transduced on days 2/3 with retroviral vectors expressing GFP, or GFP with A1, and then recultured without any further stimulation. (a) On day 5 of primary culture, GFP<sup>+</sup> T cells were sorted and analyzed for A1 and β-actin expression. Protein amounts were determined by densitometry and are shown relative to the expression in wild-type T cells transduced with control vector (taken as 1). (b) T cells recovered from primary cultures on day 5 were recultured in the absence of any further stimulation for 4 days. GFP<sup>+</sup>Vβ5<sup>+</sup> T cell recovery normalized to take into account differences in initial transduction efficiency between cultures. Numbers of GFP<sup>+</sup> cells present on day 4 were assigned a value of 100%, and numbers surviving on day 6 and day 8 were used to calculate the percentage recovery relative to day 4. Data represent the mean ± s.d. from three separate experiments (<i>p</i>>0.05).</p>