Growth-stimulating activity toward HEL cells on coculture with stable human ICAM-1 expressing CHO-K1 cells. (A) Phenotypic analysis of stable human ICAM-1-expressing CHO-K1 cells. Stable human ICAM-1–expressing CHO-K1 cells were prepared by the method described under Materials and Methods. The cells were stained with anti-human ICAM-1 MoAb and FITC-conjugated antimouse IgG F(AB′) fragment, successively, and then analyzed by flow cytometry. The shaded peak indicates the expression of ICAM-1 on the stable transformant and the dotted line indicates that on mock-transfected CHO-K1 cells. (B) Growth-stimulating activity toward HEL cells on coculture with stable ICAM-1–expressing CHO-K1 cells. HEL cells (5 × 103cells) were seeded onto irradiated confluent layers of HESS-5 cells (HESS-5), CHO-K1 cells (CHO-K1), and stable human ICAM-1–expressing CHO-K1 cells (CHO-ICAM1) in 200 μL of RPMI-1640 medium supplemented with 0.1% BSA in triplicate. After 3 days of culture, the3H-thymidine incorporation by HEL cells was measured by the method described under Materials and Methods. The results are expressed as mean values ± SD of the mean.
