Abstract: Objective To investigate the regulatory effect of ATP-binding cassette transporter A1 (ABCA1) knockdown on inflammatory response induced by Pam3CSK4 in mouse mononuclear macrophage RAW264.7 cell line. Methods A mouse mononuclear macrophage RAW264.7 cell line with stable ABCA1 knockdown was constructed and stimulated with Toll-like receptor 2 (TLR2) ligand Pam3CSK4, and the changes in the transcriptional levels of the proinflammatory and antiinflammatory cytokines were analyzed in this cell model. Results In RAW264.7 cells, ABCA1 knockdown significantly upregulated Pam3CSK4 stimulation-induced expressions of IL-1β, TNF-α and IL-6 and also enhanced the expression of transcription factor cAMP-dependent transcription factor 3 (ATF3) without obviously affecting the expressions of the transcription factors ATF1, ATF2, ATF4 or ATF5. Conclusion ABCA1 knockdown in macrophages may have both proinflammatory and anti-inflammatory effects. ABCA1 knockdown up-regulates the transcription of ATF3 possibly through a mechanism that is different from that for the other members of the ATF protein family.