Cytokine production in the infrapatellar fat pad: another source of cytokines in knee synovial fluids

Results: Infrapatellar fat pads were found to contain various protein levels of bFGF, VEGF, TNFα, and IL6. Further, gene expressions for these cytokines were detected by RT-PCR. Immunohistochemistry and in situ hybridisation showed that the expressions of both bFGF and VEGF were localised in immature adipocytes, interstitial undifferentiated mesenchymal cells, and vascular endothelial cells. Conclusion: The production of bFGF, VEGF, TNFα, and IL6 in the infrapatellar fat pad was demon- strated. Although synovial cells and articular chondrocytes are thought to be primary sources of cyto- kines found in knee synovial fluids, the results suggest that they may also originate from this fat pad.