To examine the biological significance of tumor-associated B7-H1 in cancer immunity,we co-cultured CFSE-labeled T cells isolated from human PBMCs alone (T cells only) orwith different numbers of A549 cells in the absence (1:2 +A549, 1:4 + A549, or 1:8 +A549) or presence of anti-B7-H1 antibody (1:2 +anti-B7-H1, 1:4 + anti-B7-H1, or 1:8 +anti-B7-H1). This evidence concerns the gene CD274 and neoplasm.