Abstract
Purpose:
To characterize the phenotype, function and cytokine production of THP-1 derived macrophages when exposed to the most common preservative in eye drops, benzalkonium chloride (BAK).
Methods:
Macrophages, obtained after differentiation of THP-1 cells, a human monocytic leukemia cell line, with phorbol myristate acetate (PMA) were exposed for 24 hours to 10-5% benzalkonium chloride (BAK) or phosphate buffered saline (PBS) as control. The expressions of CD11b, CD11c, CD33 and CD54/ICAM-1 were evaluated using immunohistochemistry and flow cytometry (FCM). Phagocytosis function was analyzed using carboxylate-modified fluorescent microspheres and FCM. Cytokine production was quantified in culture supernatants using a human cytokine array.
Results:
Stimulation of macrophages with BAK increased CD11b and CD11c expressions and decreased CD33 as well as they increased their phagocytosis function and their secretion of cytokines in supernatants especially CCL1, CCL4/MIP-1β, TNF-α, soluble CD54/ICAM-1 and IL-1β.
Conclusions:
In vitro, a low concentration of BAK induced a direct stimulating effect on macrophages, increasing phagocytosis, cytokine release and expressions of CD11b and CD11c. Long-term exposure to low concentrations of BAK should be considered as a stimulating factor responsible for inflammation through macrophage activation.
Keywords: 621 ocular irritants •
555 immunomodulation/immunoregulation •
491 cytology