Evidence for the presence of angiotensins in normal, unstimulated alveolar macrophages and monocytes.

The presence of angiotensins was demonstrated in normal unstimulated alveolar macrophages and monocytes from both mice and rats. These peptides were partially purified from cell homogenates by ion exchange chromatography and identified as being [Ile5] angiotensin I (Ang I), [Ile5] angiotensin II (Ang II) and to a lesser extent [Ile4] angiotensin III (Ang III) using high performance liquid chromatography (HPLC). Based on the present data both alveolar macrophages and monocytes expressed Ang I as quantified by a specific and sensitive radio-immunoassay (RIA) from the HPLC eluates. In contrast to this, alveolar macrophages from both mice and rats exhibited a fairly low, if detectable Ang II content. It seems reasonable to suggest that, in contrast to monocytes, macrophages do not generate and/or incorporate Ang II appreciably, at least in their resting stage. Although it is still not obvious whether these mononuclear phagocytes generate or simply capture angiotensin(s) from the blood pool or from the tissues; they must serve as in vivo target cells for the angiotensin system, at least for the plasma or tissue clearance of these molecules.