B-CLL cells efficiently express CD40L, OX40L, CD80, and CD86 after coculture with CD40L/OX40L-expressing MRC-5. (A) Expression of hCD40L and hOX40L on transduced MRC-5 24 hours after transduction with both vectors simultaneously. No difference was observed when transducing the MRC-5 with each single vector separately (data not shown). (B) Representative sample (of 7 tested) of hCD40L and hOX40L expression on B-CLL cells before and after the coculture on CD40L/OX40L-expressing MRC-5. (C-E) Expression of CD80, CD86, CD40L, and OX40L before (time 0, ▦) and 24 hours after (▪) the coculture with CD40L/OX40L-expressing (C) MRC-5, (D) CD40L-expressing MRC-5, and (E) OX40L-expressing MRC-5, respectively. Each bar represents the mean + SD percentage of positive viable cells gated on CD5⁺/CD19⁺ B-CLL cells (7 donors tested). ^*P < .005.