Toru Okajima

In vitro angiotensin-converting enzyme and interleukin-1 production by epithelioid cells isolated from induced rabbit lung granuloma

We attempted in this experiment to culture epithelioid cells isolated from granuloma induced in the lung of female rabbits that had been injected intravenously with Freunds complete adjuvant. The morphologic findings of isolated cells included abundant rough-surfaced endoplasmic reticulum, mitochondria, Golgi complexes, electron-dense lysosomes, and numerous cytoplasmic processes on the cell surface. Enzymatically these cells were positive for acid alpha-naphthyl acetate and beta-galactosidase staining. These findings coincided with the expected morphologic and enzymatic characteristics of epithelioid cells examined in vivo. Cells isolated from this granuloma are thought to be more than 86% epithelioid cells. Additionally, 14.4 +/- 4.3% of the epithelioid cells showed phagocytosis of latex beads, low when compared with the 83.9 +/- 5.2% value of alveolar macrophages obtained from rabbits injected with adjuvant 4 weeks before sacrifice. The isolated epithelioid cells were incubated for 24 h without decrease in cell population. Their culture supernatants showed 1.86 +/- 0.38 units/ml of angiotensin-converting enzyme (ACE) activity, which was inhibited by cycloheximide. The culture supernatants also showed interleukin-1 (IL-1) activity levels of 6411 +/- 914 cpm without lipopolysaccharide (LPS) stimulation. This increased to 21,766 +/- 3026 cpm with LPS stimulation. In view of these results, we believe it is possible to incubate epithelioid cells for up to 24 h during which time they will produce ACE and IL-1 in the culture supernatants.