Incubation of human proximal tubular epithelial cells with 2 different monoclonal FLCs (κ2 and λ2) increases the production of MCP-1 through activation of the NF-κB pathway. (A) Confocal laser scanning microscopy using the LSM 710 confocal microscope (Carl Zeiss MicroImaging) and the accompanying LSM 710 ZEN software demonstrated nuclear localization (arrowheads) of RelA (p65) in cells within 6 hours of exposure to κ2 and λ2 FLCs (1 mg/mL). The white bar represents 10 μm. (B) Increase in MCP-1 production induced by 24-hour incubation of renal epithelial cells with the FLCs was inhibited by PDTC, an inhibitor of NF-κB. *P < .05 compared with samples incubated in medium alone (control) and in medium containing the corresponding FLCs and PDTC; n = 6 experiments in each group.