The sub-confluent cultures of HK-2 cells in 6-well plate (Falcon, Franklin Lake, NJ) were treated with recombinant human TGF-b 1 (R&D Systems, Minneapolis, MN, USA) at concentrations of 10.0, 1.0 and 0.1 ng/ml for 24 hrs. Next, the cells were washed three times with phosphate-buffered saline (PBS). Then, PBMCs (2610 5 ) were added to each well for co-culture for 24 hrs. For blocking the interaction of LFA-1 on PBMCs and ICAM-1 on HK-2 cells, HK-2 cells were pre-incubated for 20 minutes at 37uC with 20 mg/ml anti-ICAM-1 monoclonal antibody (mAb) (clone: 6.5B5, Santa Cruz Biotechnology Inc., Santa Cruz, CA) or naïve PBMCs were pre-incubated for 20 minutes at 37uC with mg/ml anti-LFA-1 mAb (clone TS1/22, kindly provided by Dr. M. Shimaoka, IDI Harvard Medical School, Boston) before coculture. Pre-incubation with HK-2 and PBMCs with mouse IgG 1 isotype control mAb (clone MOPC-31C, BD, San Jose, CA) was used for control experiments.