Fig. (6) Growth inhibition by anti-OX40 ligand and anti-OX40 antibody. (A) Expression of OX40 ligand or OX40 on HUVEC or HUATTAK as determined by flow cytometry. (B) Anti-OX40 ligand antibody completely inhibits the growth of HU-ATTAK. HU-ATTAK cells in quadruplicate culture were cultured in the presence of 0 µg/ml (□), 1 µg/ml (▲), 10 µg/ml(●) and 30 µg/ml(■) of OX40 ligand antibody. The negative control was the absence of HUVEC (○). Cells were counted on days 3, 6 and 8. This is a representative of two independent experiments. Cell numbers are plotted using a log scale. (C) Anti-OX40 antibody partially inhibits the growth of HU-ATTAK. HU-ATTAK cells in quadruplicate culture were cultured in the presence of 0 µg/ml (□), 1 µg/ml (▲), 10 µg/ml (●) and 30 µg/ml (■) of OX40 antibody. The negative control was without HUVEC (○). Cells were counted on days 3, 6 and 8. This is a representative of two independent experiments. Cell numbers are plotted using a log scale.