Effects of various inducers on the expression of P2X7 receptor in human peripheral blood mononuclear cells

Regulation of P2X7 receptor expression is of interest because activation of this receptor by extracellular ATP triggers a wide variety of cell functions in leukocytes. However, its expression and modulation in human peripheral blood mononuclear cells (PBMC) and monocytes remain unclear. RT-PCR was used to detect the constitutive level of P2X7 receptor and the levels upon stimulation with bacteria, bacterial product, mitogen and various cytokines in human PBMC and monocytes. P2X7 receptor mRNA was detected in PBMC and monocytes. P2X7 receptor expression in PBMC was up-regulated by interleukin-2, -4, -6 (IL-2, IL-4, IL-6) tumour necrosis factor-alpha (TNF-alpha), lipopolysaccharide (LPS) and heat-inactivated Staphylococcus aureus Cowan strain I (SAC). However, interferon-gamma (IFN-gamma), granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF) and phytohemagglutinin-M (PHA-M) had little effect on the expression of P2X7 receptor. Furthermore, LPS and M-CSF could up-regulate P2X7 receptor expression in monocytes, while IFN-gamma, TNF-alpha and GM-CSF had weak effects, but pretreatment with these inducers could not further enhance LPS-stimulated P2X7 receptor expression in monocytes. The results obtained demonstrate that inflammatory stimuli drive P2X7 expression, thus supporting the hypothesis that P2X7 receptor may play a role in the inflammatory responses against bacteria infection, which need further verification.