We investigated the conformational activation change of LFA-1 on PBMCs by HK-2 cells after stimulation with TGF-b 1 (0.1 ng/ ml). We employed flow cytometry using anti-LFA-1 mAb (clone: TS1/22) to detect total LFA-1 on PBMCs and anti-active form LFA-1 mAb (clone: AL-57) that reacted only with the active form of LFA-1 but not with the resting form of LFA-1 to detect conformational activation of LFA-1 on PBMCs. After co-culture with HK-2 cells stimulated by TGF-b 1 (0.1 ng/ml) for 30 minutes, AL57-positive cells were significantly increased , whereas TS1/22positive cells were not changed on PBMCs. AL57-positive cells on PBMCs did not change by co-culture with HK-2 cells without TGF-b 1 and TGF-b 1 alone ( Figure 3A ). Next, we investigated the effect of CCL3 and CXCL12 of HK-2 cells on the LFA-1 activation on HK-2 cells. CXCL12 and CCL3 on HK-2 cells were knocked down by transfection of CXCL12-siRNA or CCL3-siRNA, respectively. Non-treated (Mock) HK-2 cells and nontargeted-siRNA-transfected (Control) HK-2 cells served as controls. CXCL12 knockdown (CXCL12 KD) HK-2 cells did not increase CXCL12 expression regardless of TGF-b 1 stimulation. CCL3 knockdown (HK-2-CCL3 KD) HK-2 cells did not increase CCL3 expression regardless of TGF-b 1 stimulation ( Figure S1 ). PBMCs were co-cultured with CXCL12 KD, CCL3 KD, Control or Mock HK-2 cells after stimulation with TGF-b 1 (0.1 ng/ml) for 30 minutes. Significantly less AL57-positive cells were detected among PBMCs after co-culture with CXCL12KD HK-2 cells than among CCL3KD, Control and Mock HK-2 cells ( Figure 3B ).