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Paralysis of phagocyte migration due to an artificial blood substitute
Abstract:
We investigated the effect of a candidate artificial blood substitute, Fluosol-DA (FDA), on human neutrophil function in a serum-free medium. In a 50% (vol/vol) mixture with polymorphonuclear cells (PMN), FDA had no effect on PMN viability, phagocytosis, superoxide anion generation, degranulation, or bactericidal activity. In striking contrast, the random migration and chemotaxis of PMN to both f-Met-Leu-Phe (fMLP) and activated serum were inhibited by 98% +/- 2%, 95% +/- 2%, and 88% +/- 6%, respectively. Inhibition of chemotaxis by FDA required no preincubation, was dose-dependent (50% inhibition [ID50] with a 14% vol/vol mixture with FDA), and was fully reversible by washing PMN free of FDA after one hour but not after 18 hours of incubation (32% +/- 11% inhibition of chemotaxis). FDA itself was not chemotactic and did not impair either the chemotactic activity or binding of fMLP to PMN. FDA also inhibited PMN adhesion (ID50, 9 +/- 1 vol/vol%). The inhibitory component of FDA was found to be its detergent additive, Pluronic F-68, which inhibited random migration, chemotaxis, and adhesion with ID50s of 1.4, 2.4, and 2.9 mg/mL, respectively (equivalent to FDA concentrations of 5, 9, and 11 vol/vol%, respectively). All the other components of FDA were noninhibitory. Plasma samples from humans injected with 8 mL/kg FDA and plasma samples from rabbits injected with 16 mL/kg FDA or an equivalent concentration of Pluronic F-68, when mixed with autologous PMN, also severely inhibited PMN chemotaxis. We conclude that exposure of PMN to clinically relevant concentrations of FDA inhibits PMN migration, presumably due to inhibition of adhesion. The inhibitory effect is entirely due to the detergent, Pluronic F-68. Artificial blood substitutes containing Pluronic F-68 may compromise the ability of PMN to prevent or effectively control microbial infections.
Insights
The artificial blood substitute Fluosol-DA (FDA) significantly impairs neutrophil migration and adhesion, primarily due to its Pluronic F-68 component. This finding suggests potential risks for infection control when using FDA-based blood substitutes.
Area of Science:
- Immunology
- Biomedical Engineering
- Pharmacology
Background:
- Artificial blood substitutes are crucial for transfusion medicine.
- Fluosol-DA (FDA) is a perfluorocarbon-based oxygen carrier.
- Neutrophil function is critical for host defense against infection.
Purpose of the Study:
- To investigate the impact of Fluosol-DA (FDA) on human neutrophil function.
- To identify the specific component within FDA responsible for any observed effects.
- To assess the clinical relevance of FDA's effects on neutrophil migration and adhesion.
Main Methods:
- Human neutrophils (PMN) were incubated with FDA in serum-free medium.
- Assays measured PMN viability, phagocytosis, superoxide generation, degranulation, bactericidal activity, random migration, chemotaxis, and adhesion.
- The effects of FDA components, particularly Pluronic F-68, were isolated and tested.
Main Results:
- FDA did not affect PMN viability or key microbicidal functions.
- FDA significantly inhibited PMN random migration (98%) and chemotaxis (95-98%) in a dose-dependent manner.
- The detergent Pluronic F-68 was identified as the sole inhibitory component, affecting migration and adhesion.
Conclusions:
- Clinically relevant concentrations of FDA inhibit neutrophil migration and adhesion, primarily due to Pluronic F-68.
- This inhibition of neutrophil function may compromise the immune system's ability to combat microbial infections.
- Blood substitutes containing Pluronic F-68 warrant careful consideration regarding their impact on host defense mechanisms.