Fig. (2) IL-1β secretion from monocytes/macrophages (n=3-4) and osteoclasts (n=8), challenged with particles and ions with or without LPS for 24 hours. PBMCs are obtained from human whole blood, monocytes/macrophages are isolated from PBMCs, and challenged with metal particles or ions, with and without LPS, for 24 hours. To form osteoclasts, monocytes/macrophages are cultured with M-CSF (50 ng/ml) and RANKL (100 ng/ml) for 6-7 days, and challenged with metal particles or ions, with and without LPS, for 24 hours. 24 hours later, IL-1β cytokine secretion is assessed in supernatants of each condition. (A) Monocytes secreted >3 orders of magnitude more IL-1β compared to osteoclasts, where osteoclast responses (black bars) are barely evident (asterisks indicate p < 0.0002 of monocytes vs osteoclasts). (B) Comparison between the cytokine secretion of primed/co-challenged monocytes/macrophages and osteoclasts (asteriks indicate statistical significance of monocyte vs osteoclasts comparison for each challenge condition at p < 0.0001), (C) Comparison between the cytokine secretion of primed/co-challenged and unprimed (no LPS) monocytes/macrophages, and (D) Comparison between the cytokine secretion of primed/co-challanged and unprimed osteoclasts. Note: Statiscal comparison of adjacent bars (black vs white) are indicated by “*” corresponding to p < 0.05 or as indicated.