Fluorescence intensity is shown on a standard logarithmic scale. Human T cells were CFSE-labeled as
described in detail (Kober et al., 2008). Irradiated T cell stimulator cells (2 × 106/ml) were incubated with 0.5 μM working solution of CellTracker™ Orange CMTMR (5-and 6 (4-chloromethyl-benzoyl-amino-tetramethylrhodamine) mixed isomers for 30 min at 37 °C in a CO2 incubator. The reaction was stopped by washing once with pre-warmed medium. For double-immunoflourescence CMTMR-labeled stimulator cells (8 × 104/well) and CFSE-labeled T cells (4 × 105/well) were co-cultured in a Selleckchem Bioactive Compound Library 24-well cell culture plate in phenolred-free cell culture medium for 24 h or 48 h. To visualize the stimulator cell–T cell interaction at a higher magnification, cells were co-cultured for 24 h, fixed in 4% paraformaldehyde and washed once with medium. Subsequently, cells were analyzed by laser scanning microscopy (LSM 410, ZEISS) (Kriehuber et al., 2001). CellTrace™ CFSE and CellTracker™ Orange CMTMR were both purchased from Molecular Probes (Eugene, OR). cDNA derived from hybridoma cells producing the anti-human CD3 antibody OKT3 (ATCC, Manassas, VA) was subjected to PCR amplification using primer pairs specific for the variable regions FDA approved Drug Library cost of the heavy chain (VH-for 5′ GGAATTCGCTAGCCCAGGTCCAGCTGCAGCAGTCT 3′, VH-rev 5′ GGGGGATCCGGTGACCGTGGTGCCTTGGCCCCAGTA 3′) and light chain (VL-for 5 GGAATTCGAGCTCCCAAATTGTTCTCACCCAGTCTCCA 3′ and VL-rev
5 GGGATCCCCACCGCCCCGGTTTATTTCCAACTTTGT PJ34 HCl 3′). The resulting PCR products were digested with Nhe I plus BstE II (VH) and Sac I plus BamH I (VL) and joined via a Sac I to BstE II fragment encoding a (G4S)3-linker by ligation. Two distinct DNA-fragments were generated by employing additional PCR and ligation steps: CD5L-OKT3scFv-CD28 encoded the OKT3-single chain antibody fragment flanked by the CD5 leader sequence and a BamH I to Not I fragment encoding the transmembrane and intracellular domains of human CD28, which was amplified using the primer pair (5′ CGCGGGGGATCCCCCAAGTCCCCTATTTCCCGG 3′ and 5′ GCGCCCGCGGCCGCTTTAGGAGCGATAGGCTGCGAAGT 3′), whereas CD5L-OKT3-CD14 encoded the OKT3-single chain antibody fragment flanked by the CD5 leader peptide and the leaderless
human CD14 molecule generated by fusing a CD14 BamH I to Nhe I fragment, which was amplified using the primer pair (5′ CGCGGGGGATCCCACCACGCCAGAACCTTGTGA 3′ and 5′ CCTTGAGGCGGGAGTACGCT 3′) to the Nhe I to Not I fragment of CD14 cDNA. Both constructs were cloned into the retroviral expression vector pMMP and the integrity of the synthetic expression constructs was confirmed by DNA-sequence analysis. The nucleotide sequences encoding the surface expressed anti-CD3 antibody fragments have been submitted to GenBank: accession ns. HM208751 – CD5L-OKT3-scFv-CD28 (protein_id ADN42858); and HM208750 – CD5L-OKT3-scFv-CD14 (protein_id ADN42857). Bw5147 cells were retrovirally transduced to express the CD5L-OKT3-scFv-CD28 or the CD5L-OKT3-scFv-CD14 constructs.