Studies comparing endogenous and recombinant serum amyloid A (SAA) have generated conflicting data on the proinflammatory function of these proteins. In exploring this discrepancy， we found that in contrast to commercially sourced recombinant human SAA1 (hSAA1) proteins produced in ， hSAA1 produced from eukaryotic cells did not promote proinflammatory cytokine production from human or mouse cells， induce Th17 differentiation， or stimulate TLR2. Proteomic analysis of -derived hSAA1 revealed the presence of numerous bacterial proteins， with several being reported or probable lipoproteins. Treatment of hSAA1 with lipoprotein lipase or addition of a lipopeptide to eukaryotic cell-derived hSAA1 inhibited or induced the production of TNF-α from macrophages， respectively. Our results suggest that a function of SAA is in the binding of TLR2-stimulating bacterial proteins， including lipoproteins， and demand that future studies of SAA employ a recombinant protein derived from eukaryotic cells.