Angiotensin II type 1 receptor expression on human leukocyte subsets: a flow cytometric and RT-PCR study

The renin-angiotensin system plays a key role in the regulation of cardiovascular functions and in particular angiotensin II type I receptor (AT(1)R)-operated pathways are involved in the modulation of inflammation in the vascular wall. In the present study we assessed the pattern of expression of AT(1)Rs on different human circulating leukocyte subsets. Venous blood was obtained from healthy male subjects. Leukocyte subsets were purified by immunomagnetic cell sorting or identified in whole blood using multiparametric cytometric analysis. RT-PCR analysis showed that AT(1)R mRNA was expressed in polymorphonuclear leukocytes (PMNs), monocytes, B-lymphocytes, and, to a lesser extent, T-lymphocytes. Flow cytometric analysis revealed that the frequency of expression of AT(1)Rs was: PN/FNs > monocytes >= B-lymphocytes >> T-lymphocytes, while receptor density per positive cells was: PMNs >= B-lymphocytes > T-lymphocytes >= monocytes. AT(1)Rs are expressed on PMNs, monocytes, T- and B-lymphocytes, however the expression pattern is peculiar to each subset, possibly suggesting distinct roles in the various cell types. Investigating the expression and the functional role of AT(1)Rs on circulating leukocyte subsets, as well as their possible modifications in disease conditions before and after pharmacological treatments, is likely to provide novel clues to the comprehension of the mechanisms involved in the therapeutic efficacy of currently available agents.