Perﬂuorochemical liquids modulate cell-mediated inﬂammatory responses Britt Nakstad, MD, PhD; Marla R. Wolfson, PhD; Thomas H. Shaffer, PhD; Hanne Kähler, MD; Rolf Lindemann, MD, PhD; Drude Fugelseth, MD, PhD; Torstein Lyberg, PhD N umerous investigations have shown that perﬂuorochemi- cals (PFC), as either pure in- ert liquids (1–13) or emul- sions (14, 15), can dissolve adequate oxygen and carbon dioxide to support res- piration of entire mammals, isolated or- gans, and tissues. All of the evidence to date indicates that the respiratory system plays a key role in many of the biomedical applications of PFC liquids. With respect to emulsions, the lungs provide the pri- mary route of PFC elimination from the body, whereas, for liquid ventilation, the lungs are the route of entry. PFC liquids have been claimed to be biologically inert and nonbiotransform- able; however, when used as a breathing medium, small amounts diffuse into blood by passing across the lung epithe- lium to dissolve in blood lipids (8, 9, 16 –18). PFC liquids are practically in- soluble in water (19, 20), and their abil- ity to absorb in the blood and to vola- tilize from the lungs depends on their lipid solubility and vapor pressure (7– 13, 20, 21). Thus, essentially all of the PFC in blood and tissues is dissolved in lipids (17–19) and results in low blood and tissue concentrations (4, 7–10). Qualitative studies of cultured hu- man monocytes after exposure to per- ﬂubron (PFB) PFC emulsion and alve- olar macrophages after in vivo exposure to neat PFB PFC liquid suggest that PFC liquids may be sequestered into cells (22–24). By using human umbili- cal vein endothelial cells and neutro- phils in a Biocoat system (Biocoat, Fort Washington, PA) to prevent direct con- tact of the endothelial cell with the perﬂubron PFC liquid phase, Woods et al. (25) demonstrated a signiﬁcant re- duction in surface levels of E-selectin and intercellular adhesion molecule-1 after proinﬂammatory activation. Ob- raztsov et al. (26) demonstrated that the modulating effect of perﬂubron on inﬂammatory responses is the result, in part, of the lipid solubility of PFC sup- porting partitioning into cell mem- branes. Preliminary data have been re- ported recently relating intracellular FC-75 PFC uptake and decreased cyto- kine release of stimulated cultured ro- dent alveolar macrophages harvested after in vivo PFC exposure (24). How- ever, no data exist to evaluate the inﬂu- ence of PFC liquids on blood leukocytes or the various cell types of alveolar lin- ing ﬂuids as a function of PFC liquids with different physicochemical proper- ties, a range of PFC concentrations, or subtypes of cell populations. From the Department of Pediatrics (BN, RL, DF) and Research Forum (BN, HK, TL), Ullevål University Hospital, Oslo, Norway; and the Departments of Phys- iology and Pediatrics (MRW, THS), Temple University School of Medicine, Philadelphia, PA. Address requests for reprints to: Marla R. Wolfson, PhD, Temple University School of Medicine, Depart- ment of Physiology, 3420 North Broad Street, Phila- delphia, PA. E-mail: marlar@astro.ocis.temple.edu Copyright © 2001 by Lippincott Williams & Wilkins Objective: To examine whether chemically different perﬂuoro- chemical liquids (PFC) (perﬂuorodecalin [PFD]; perﬂubron [PFB]) induce inﬂammatory responses in blood leukocytes. Setting: University research laboratory. Design: Whole blood from 12 healthy adults was incubated with increasing PFC concentrations and/or bacterial lipopolysac- charide. Measurements and Main Results: Adhesion molecules (CD62L, CD11b), reactive oxygen species, and cytokine responses in rest- ing and activated leukocyte subtypes were studied. Scanning and transmission electron microscopies were performed. At the high- est concentrations, PFB stimulated a signiﬁcant increase in rest- ing monocytic reactive oxygen species production; all types of blood leukocytes were unresponsive to PFD. Neither PFB nor PFD changed CD62L expression; PFB increased CD11b expression in monocytes and granulocytes. PFD induced a small though signif- icant increase in interleukin-8 secretion. When simulating a con- dition in which patients with severe lung disease or sepsis would be ventilated with PFC, neither PFB nor PFD plus lipopolysaccha- ride stimulated tumor necrosis- or interleukin-8 production above levels induced by lipopolysaccharide alone, but rather demonstrated a trend for decreased tumor necrosis factor- production. Expression of CD11b and CD62L and the production of reactive oxygen species were not changed beyond the levels induced by lipopolysaccharide alone. As a morphologic correlate to the above proinﬂammatory changes, surface-bound blebs and intracellular vacuoles were seen by electron microscopy. Conclusions: At PFC concentrations comparable with those in blood during liquid ventilation, PFC liquids did not induce vari- ables associated with inﬂammation. In the presence of high PFC concentrations, simulating the condition in which bronchoalveolar cells are exposed to PFC, monocytes may be induced by PFB to produce reactive oxygen species, and blood leukocytes induced by PFB to express CD11b and by PFD to secrete interleukin-8; the presence of either PFC attenuated tumor necrosis factor- pro- duction after lipopolysaccharide stimulation. (Crit Care Med 2001; 29:1731–1737) KEY WORDS: perﬂuorochemical; leukocytes; adhesion molecules; oxygen radicals; cytokines; perﬂubron; perﬂuorodecalin; inﬂam- mation 1731 Crit Care Med 2001 Vol. 29, No. 9