Highly purified human peripheral blood monocytes produce IL-6 but not TNFalpha in response to angiotensin II

Monocytes produce pro-inflammatory cytokines in response to Angiotensin II (AngII).

AngII has been suggested by many to be pro-inflammatory and likely to contribute to the migration of leukocytes in patients with cardiovascular conditions.

Monocytes were purified from peripheral blood mononuclear cells (PBMCs) by negative selection using antibodies conjugated to magnetic beads. Detection of CD14(+) and AT(1)R expression was achieved by double-labeling flow cytometry. Highly purified monocytes were then stimulated with AngII (6 and 24 h) to assess IL-6 and TNF-α transcript levels by qRT-PCR and protein secretion by ELISA.

Monocytes comprised 9.7 ± 2.0% of the PBMCs. Monocyte isolation by negative selection yielded a purity of up to 99.8%. We demonstrated AT(1)R expression on 9.5 ± 0.3% of highly purifed CD14(+)/CD16(-) monocytes. Stimulation of highly purified monocytes with AngII resulted in increased transcript levels of IL-6 at 6 h but not at 24 h, and increased secretion of IL-6 in a dose-dependent manner compared with controls (p <0.01). Conversely, there was no increase in TNF-α mRNA transcripts or protein secretion.

We provide evidence that a CD14(+)/CD16(-) subset of highly purified human monocytes express AT(1)R and respond to AngII exposure in vitro by producing IL-6 but not TNF-α.